Frequently Asked Questions

Software Client

Does BitTorrent contain Spyware, Adware or Malware?

No, it does not.

Spyware is software that is installed silently and without consent on a user’s computer, and which collects personal information about the user or usage of the computer.

Adware is software that is designed to intrude upon the user experience on a computer with advertisements and promotions that cannot be easily avoided or disabled.

Malware (malicious software) is software that is specifically designed to attack and harm a computer’s data, applications or operating system.

BitTorrent software downloads contain no spyware, adware, or malware of any kind. Not today and not ever.

Does BitTorrent support HTTPS (SSL) or UDP trackers?

BitTorrent supports SSL (for trackers and RSS), but not UDP trackers. UDP tracker support is not likely, due to many flaws with the UDP tracker spec.

Does BitTorrent support DHT or Peer Exchange?

BitTorrent supports both DHT and Peer Exchange. It respects only the private flag included in the .torrent. The private flag will disable both PEX and DHT.

BitTorrent does NOT support private flags given by the tracker in the announce response! It is a dirty fix, and is EXTREMELY unreliable. Only the private flag embedded into the torrent will be supported because it is reliable and relatively secure by design.

Does BitTorrent automatically ban peers after a certain number of hashfails?

Yes, it does, after 5 hashfails. It will ban and kick the peer for the entire session. To reset the bans on the torrent, right click the torrent, Advanced -> Reset Bans.

How can I make BitTorrent report a different IP to the tracker? I'm behind a proxy and need this function.

Go to BitTorrent and put in the value in the box next to "IP to report to tracker." This function is NOT for when you are behind a NAT, the tracker can automatically determine your IP in that case. It's only when your WAN IP (as in, the actual internet connection's IP) is different from what the tracker sees. However, some trackers WILL ignore this value, so it may not help you at all.

What does Bandwidth Allocation do?

This is an option that makes BitTorrent allocate less or more bandwidth towards a torrent. This only affects upload, and only if an upload cap is set.

I get "Error: Access Denied" / "Error: The process cannot access the file because it is being used by another process"

Error: Access Denied can be caused by numerous things. The most common cause seems to be Google and MSN Desktop. A possible fix is turn off the indexing feature, or to uninstall them. Excluding the download folders from indexing should work.
The best solution is to uninstall Google/MSN Desktop.

WinZIP Quickfind has the same effect as Google/MSN Desktop. It must be disabled.

Another possibility is that you inadvertently have two copies of BitTorrent running and using the same torrents. Open the Task Manager (CTRL SHIFT ESC or right click on the system clock -> Task Manager), and see if there's more than one bittorrent.exe in the Processes tab. If this is the case, close both of them and start up BitTorrent again.

Yet another possibility is that you are viewing the folder while it's downloading, and Explorer is set to thumbnail mode. If this is the case, Explorer would try to access these files while viewing the folder in Thumbnail mode, and lock out BitTorrent from writing. The solution is to not view the folder until the download is finished, don't use Thumbnail mode, or turn off flush files. Explorer may also be trying to read the media files (MP3, AVI and so on) in the folder to make thumbnails, show you information about them, or preview them. You can unregister the media indexer (Start -> Run -> regsvr32 /u shmedia.dll ), and/or unregister the image indexer (Start -> Run -> regsvr32 /u shimgvw.dll ) as an alternative for either case, not view the folder, or turn off flush files.

How can I change the number of active torrents/downloads?

Open the options, go to Queueing, and change the values for "Maximum number of active torrents (upload or download)" and "Maximum number of active downloads"

How do I change the number of connections BitTorrent uses?

Go to BitTorrent and set "Global maximum number of connections" and "Maximum number of connected peers per torrent."

How is the share ratio shown for torrents that are started fully complete?

It starts at 0.000 instead of ∞ to give you an estimate of how much of the file has been distributed. It is amount uploaded / file size.

How can I rename a torrent's folder?

If you're adding a new torrent, you can rename it by simply changing the save path (the folder doesn't have to exist). If the torrent already exists, stop the torrent, rename the folder to whatever you like, then in BitTorrent, right click on the torrent, pick Advanced -> "Set download folder", and point it to the newly renamed folder. Then, simply start the torrent again (no need to force re-check).

Why does my download seem stuck at a certain point? What does availablity mean?

That number tells you how many unique copies of the file are available between yourself and the peers you're connected to. If this is less than 1, you most likely will not be able to complete the torrent. The only thing you can do is wait and hope a seeder hops onto the torrent to allow you to complete it. You can also try and request a "reseed" on the tracker's forum. Sometimes, this may never happen because the torrent was abandoned, and you may need to find the torrent elsewhere.

How do I fix Error: Unable to save the resume file?

Simply create two blank files named "settings.dat" and "resume.dat" (without the quotes) in the same folder bittorrent.exe is saved in. Make sure Windows is not hiding the file extension when creating the file (in Explorer, Tools -> Folder Options -> View, uncheck "Hide extensions for known file types", hit OK)

How do I change the port BitTorrent uses?

Open the Options, click Network. You can change the port in the box next to "Port used for incoming connections." However, it takes a restart of BitTorrent to take effect. Make sure you do not run two clients with the same port!

You can choose to have BitTorrent use a different port each time you start the client, but this will not work if you are using Port Forwarding to forward a particular port.

In the BitTorrent 6.x client, what do the Network Status lights mean

The green light means all is OK (ports are forwarded and you are receiving incoming connections)

The yellow light means that you have no current incoming connections. If this never turns green, this means that your port is not forwarded. The best way to check is with the BitTorrent port checker, found in the Speed Guide. If the port checker says your port is open, then everything is most likely fine.

The red light means that BitTorrent was unable to bind a listening socket. Most likely, this means a firewall is blocking it. It's also possible that another torrent client is using this port, which will require you to change ports, or not run both clients at the same time.

Why are my torrents going so slow?

Most likely, the port you set for BitTorrent is not forwarded. If BitTorrent is displaying , then this is the case. There is also the possibility that the torrent is simply slow, especially those with small swarms (low numbers of seeders/peers). It is also possible that your firewall is blocking connections for BitTorrent. Make sure you set an exception for incoming and outgoing connections for BitTorrent in your firewall's configuration! If you block ICMPs with your firewall (Windows Firewall blocks them by default), you should allow "Destination Unreachable" to aid the proper functioning of DHT (it works anyway though).
If everything is set up fine, you will see in the status bar (to the left of DHT:) after you start a torrent and get an incoming connection. If it stays yellow, try a torrent with many peers to make sure there's enough peers in the swarm to guarantee you getting an incoming connection.

If you use an alternate firewall while on Windows XP SP1 or SP2, make sure you turn off the Internet Connection Firewall (SP1) or the Windows Firewall (SP2).
You may still have to disable the Internet Connection Firewall (ICF) or Windows Firewall / Internet Connection Sharing (ICS) service to prevent a conflict between it and your third party firewall. Control Panel -> Administrative Tools -> Services, scroll to appropriate service (ICF or Windows Firewall/ICS), right click and select Properties, select Disabled in the drop down menu and hit OK.

If you have an alternate firewall and still find yourself unconnectable after you forwarded your ports (or have no router) and attempted to configure the firewall, you may need to uninstall it, disabling never works! If you have no router and no firewall, your modem may be a router.

You may also want to turn off UPnP (found in Connection) and forward your ports manually, since some routers have flaky UPnP implementations that cause problems. Ensure your router/modem is NOT on this list!

Make sure you've used the Speed Guide and read the instructions carefully! Make absolutely sure you chose your UPLOAD speed in kilobits/s, not your download! Make sure you do not set too many upload slots OR connections per torrent. You should also try to never run more than 2-3 torrents. In general, an average 5mbit connection with 512kbit upload shouldn't have more than 90 connections per torrent, or more than 5 upload slots, especially if running more than one torrent. Experiment with these values depending on your connection speed. This is the most COMMON reason for torrents going slow, setting those options too high WILL make things slow down significantly! More connections does not mean faster speeds. Your best bet is to stick to the Speed Guide.

Make sure that TCPIP.SYS is properly patched if you've altered net.max_halfopen, and that net.max_halfopen is set lower than the value set in TCPIP.SYS! And ensure that it's still patched, because Microsoft overwrites it sometimes, forcing you to repatch.

How do I use RSS in BitTorrent 6.x?

Adding a feed
Click on the RSS button, then click Add. Paste in the feed URL and hit OK. If you want to name the feed, simply type the name in front of the URL, like so:
TV Feed|http://somesite.com/rss.xml (NO SPACE BEFORE OR AFTER THE | )

Note that the RSS Downloader will NOT consume any extra resources if you have no feeds present/enabled. Some feeds do not give direct links to the .torrent files (most notably Mininova) and as such won't work

Disabling a feed or filter
Simply uncheck the box next to the feed or filter, and it will no longer be used.

Renaming a feed or filter
You can rename a feed by selecting it, then single clicking or pressing F2. You can do the same thing for renaming filters.

Sorting filters
You can sort filters by drag and drop. Simply click, hold, and drag to wherever in the list you'd like it.

Using feeds that require HTTP authentication
For feeds that require HTTP authentication, simply use this format for the feed URL: http://username:password@sometorrentsite.com/rss.php

Using feeds that require cookies
To use feeds that require cookies, you must find the cookie for the site, and grab UID and pass from it.

IE users will find their cookies in %UserProfile%\Cookies
Firefox users will find their cookies in Tools -> Options -> Privacy -> Cookies -> View Cookies
Opera users will find their cookies in Tools -> Advanced -> Cookies, but they must scroll down manually, find doesn't work
Users of other browsers will have to consult their browser's documentation
Once you have the appropriate information, use this format for the feed URL:
http://sometorrentsite.com/rss.php:COOKIE:uid=1234;pass=asdjh12378912y3lkj

Some sites do not use uid and pass as the variables, or use additional ones, so you MUST use the exact variable name and the extra variables they specify! For example, on a certain site, it uses id, password, and secure as the cookie variables you must use.

Automatically downloading torrents
To automatically download specific torrents from a feed, you can use Favorites to specify your own filters to grab torrents. It does NOT support regular expressions. Here's a tutorial explaining the various options and how to use them (with examples).

Hit Add, then type the name of the filter.
Click on the editbox next to Filter: and add your filter. The allowed wildcards are * ? and |. An example of a filter you could use would be *MP3 Archives*
If you have a strange feed using underscores or something besides periods, you can also try something like *Go?Open*
You cannot specify the season or episode number in the filter if it is decoded by BitTorrent (check the Releases tab): you must use the episode number box, OR turn on "Filter matches original name instead of decoded name." You also can't match by group name without first using "Filter matches original name instead of decoded name." Remember, using "Filter matches original name" disables the "Episode number" function!
Not: allows you to exclude certain strings from matching. An example is you don't want releases with AC3 audio and H.264: you can write *AC3*|*H*264|*x*264* in Not: to exclude those.
If you want the torrents to automatically download and start without any further input, you MUST specify a folder in Save in:! However, if you have a path set in "Put new downloads in:" in Folder Options, you don't have to set a save folder here.
Feed: chooses what feed you want the filter to apply to; either all of them or a specific one
Quality allows you choose various qualities to match against, or allow all. You can choose more than one quality in the dropdown list.
Episode number is to download only specific ep numbers, say to avoid releases of old episodes. It does support ranges (i.e. 1x4-26).
"Filter matches original name instead of decoded name" is so that you can match based off what the original name is in the feed, instead of BitTorrent's parsed result.
Give download highest priority sets all torrents downloaded automatically through RSS to the top of the queue, making your seeds and other downloads get queued if you reach the max active torrents.
Smart ep. filter makes BitTorrent only download the first version of each new episode that matches your filter. Do NOT turn this option on if the episode number isn't parseable (shows ? for all episodes)!
Minimum interval sets a minimum interval between matches for the filter: if you set it to 2 days, BitTorrent will not download anything for at least 2 days after a match.
You can use the Reset button to make BitTorrent forget that it has downloaded episodes and the last time matched for that filter.
Label for new torrents auto-sets a label for torrents that match the filter.
All changes are automatically saved when you make them, so you don't have to do anything once you're done editing the filter.
You can select a filter and press ? to see what the last four episodes were that matched, and the last time that the filter matched something. A list of the currently matching episodes from the feeds you've defined for it is also available in the "?" dialog, so you can double-check your filter expression.

Example:

RSS Downloader Releases Tab
You can add and remove columns to the Releases tab by right clicking on them and choosing from the list. You can double click or right click -> open to download releases listed here.
means the release is less than 24 hours old.
means that the torrent was already downloaded and moved to the history.

Does BitTorrent support Protocol Encryption?

Yes. You can choose Protocol Encryption's mode of operation in BitTorrent. Here is an explanation of the various options you can choose from:

  • Disabled: Does not encrypt outgoing connections, but will accept encrypted incoming connections.
  • Enabled: Attempts to encrypt outgoing connections, but will fall back to an unencrypted mode if the connection fails.
  • Force: Attempts to encrypt outgoing connections, and will NOT fall back to an unencrypted mode if the connection fails.
  • Allow legacy incoming connections enables or disables incoming legacy (non-encrypted) connections.

All modes will accept incoming encrypted connections (and the encryption is 2-way)!

It is NOT recommended to turn off "Allow legacy incoming connections", unless you cannot have any non-encrypted connections (typically in conjunction with Forced), in which case turning off "Allow legacy incoming connections" is acceptable.

How can I make BitTorrent auto-load torrents from a specified folder?

Simply turn on "Automatically load torrents in directory:" in Other, specify the folder, and hit OK. BitTorrent will load the torrents soon after they're added to that folder, though it will ask you where to save them. If you want it to automatically save to a folder, turn on "Put new downloads in" in Downloads and specify your download folder. However, turning on "Put new downloads in" will prevent the BitComet-style add torrent dialog from showing up, unless you use File -> Add Torrent (no default save) or turn on "Always show dialog on manual add." You can turn on "Delete torrent instead of renaming, when loading" so it deletes the torrent after loading, instead of renaming it to .torrent.loaded.

Please note that the auto-load folder CANNOT be either %Appdata%\uTorrent, OR the folder you specified for "Store .torrent files in." If you use the same folders for both, you WILL have problems.

Does BitTorrent support UNC-style paths (e.g. \192.168.1.2\C$\ ) / network drives?

Yes. However, fragmentation may be higher when saving to a network drive, since allocating space across the network is not possible.

While downloading/seeding, I get "Error: The system cannot find the path specified" and BitTorrent halts the torrent.

This problem may be caused by a limitation in Windows with path lengths. Windows unfortunately limits the maximum length to 255 characters (which includes the filename). Try saving the torrent to a location closer to the drive's root, such as C: orrent.

How can I make BitTorrent use a different upload speed when seeding?

Open the options, go to Connection, check "Alternate upload rate when not downloading", and write in the value you would like in the box.

How do I change the port BitTorrent uses?

Open the Options, click Network. You can change the port in the box next to "Port used for incoming connections." However, it takes a restart of BitTorrent to take effect. Make sure you do not run two clients with the same port!

You can choose to have BitTorrent use a different port each time you start the client, but this will not work if you are using <rn:answer_xref contents="Port Forwarding" answer_id="166">Port Forwarding</rn:answer_xref> to forward a particular port.

Does BitTorrent have a scheduler to limit download and upload speeds?

Yes, in the options. It allows you to set an upload/download speed, and set it to Limit, go full speed, or stop torrents altogether by the hour/day. You can also make it turn off DHT during hours you set to "Turn off."

There is also a scheduler mode for Seeding only. Hold shift while selecting the hours and it'll turn red, which indicates seed-only mode.

Does BitTorrent support proxies?

Yes. Open the options and go to Connection. It supports SOCKS4, SOCKS5, HTTP Connect, and HTTP proxies. Peer communication proxying is supported with SOCKS4, SOCKS5, and HTTP Connect. HTTP Connect is HTTP proxies that allow arbitrary TCP connections. Not all do, which is why it's a separate item in the list.

I get "Error: Access Denied" / "Error: The process cannot access the file because it is being used by another process"

Error: Access Denied can be caused by numerous things. The most common cause seems to be Google and MSN Desktop. A possible fix is turn off the indexing feature, or to uninstall them. Excluding the download folders from indexing should work.
The best solution is to uninstall Google/MSN Desktop.

WinZIP Quickfind has the same effect as Google/MSN Desktop. It must be disabled.

Another possibility is that you inadvertently have two copies of BitTorrent running and using the same torrents. Open the Task Manager (CTRL SHIFT ESC or right click on the system clock -> Task Manager), and see if there's more than one bittorrent.exe in the Processes tab. If this is the case, close both of them and start up BitTorrent again.

Yet another possibility is that you are viewing the folder while it's downloading, and Explorer is set to thumbnail mode. If this is the case, Explorer would try to access these files while viewing the folder in Thumbnail mode, and lock out BitTorrent from writing. The solution is to not view the folder until the download is finished, don't use Thumbnail mode, or turn off flush files. Explorer may also be trying to read the media files (MP3, AVI and so on) in the folder to make thumbnails, show you information about them, or preview them. You can unregister the media indexer (Start -> Run -> regsvr32 /u shmedia.dll ), and/or unregister the image indexer (Start -> Run -> regsvr32 /u shimgvw.dll ) as an alternative for either case, not view the folder, or turn off flush files.

How do I make BitTorrent 6.x prioritize the first and last piece of a file?

Sometimes it can be helpfull to have BitTorrent prioritize getting the first and last piece of a file (to aide in previewing the file for instance). To do so, Go to the Options menu, select Preferences..., select the Advanced section, and set "bt.prio_first_last_piece" to true.

What are the BitTorrent 6.x system requirements?

The 6.x client requirements are very low. It works on Windows 95 up to XP, Vista, and 7. It works on both 32 and 64-bit Windows.
Macintosh OS X is not currently supported.

The 6.x client can work in the following Linux/Unix configurations, although it is not supported:
It is reported to work under Linux using Cedega with some issues (blue bars in Pieces and Files tab don't work, update function fails, minimize has a slight bug) if you use "Win98" mode.
It works very well under Wine 0.9.16.
It will also work under FreeBSD 6.1 using Wine 0.9.16+, but requires the GLX module to be enabled in xorg.conf.

Note: All Windows 9x systems should have at least IE 4.0 installed: it upgrades a system DLL that provides functionality for various BitTorrent functions. Be warned that Windows 95/98 are normally limited to 100 max concurrent connections.

How do I modify the disk cache options?

While the defaults should work fine, even up to 100Mbit, you may want to alter the disk cache options. You will find the options in Advanced -> Disk Cache. To see the current cache use, look at the Speed tab, and choose Disk Statistics from the drop-down list.

  • The cache size is a combined size, you cannot specify an individual size for read and write caching.
  • Reduce memory usage when cache not needed will release all the memory for the write cache when you are not downloading.
  • Write out untouched blocks every 2 minutes will control whether BitTorrent flushes the chunks from incomplete pieces to disk if the piece has been inactive for 2 minutes. Turn this off if using very large cache values or experiencing disk overload during your download (NOT if you just added the torrent, that is normal!).
  • Write out finished pieces immediately will control whether BitTorrent writes finished pieces immediately. If turned off, it will write them after a maximum of 15 seconds. Turn this off if using very large cache values or experiencing disk overload during your download (NOT if you just added the torrent, that is normal!).
  • Turn off read caching when the upload speed is low will turn off read caching when the upload speed is <100 KB/s, where the read cache is more likely to do harm than good.
  • Remove old blocks from cache will remove unused blocks after a certain amount of time has passed since they were used. Turn this off if using very large cache values.
  • Increase automatic cache size when cache thrashing will make BitTorrent increase the automatic cache size if you are experiencing disk overloads, because of very high speeds or a slow disk. Do NOT turn this on if you are experiencing disk overload while you just added the torrent, that is normal.
What does Disk Overloaded in the status bar mean?

This means that the disk was not able to keep up with the read/write speed. To fix this, you can change the options in <rn:answer_xref contents="Disk Cache" answer_id="179">Disk Cache</rn:answer_xref>.

However, if this happens when adding a torrent, it is normal, and due to a design limitation in BitTorrent, which will be fixed in the future, not because your disk is actually overloaded. It will disappear after a few minutes.

What does "Error opening Windows Firewall: 0x800706D9" mean?

This means that BitTorrent was unable to add itself as an exception to the Windows Firewall, using the standard Windows Firewall API. This most likely means that the firewall is disabled or not present. You can safely ignore this error. However, if you have another software firewall, you will still need to manually configure it to allow incoming and outgoing connections.

What does "Unable to map UPnP port to xx.xx.xx.xx:xx" mean?

This error means that BitTorrent was unable to map the port with UPnP. If you have a green status light or have forwarded your port manually, you can safely ignore this error. However, if you have a yellow/red status light, it may mean that you need to forward the port manually, or that your firewall is blocking incoming connections.

I get "Error: Element not found" and the torrent stops.

This is generally caused by having bt.compact_allocation on. Please turn it off, this option is not fully working. Use diskio.sparse_files (NTFS only) instead if you want to save space while downloading.

This can also happen if you remove/rename files from a torrent. Re-add/rename the files, or force a re-check.

I get "Error: Not enough free space on disk." when I have more than enough free space!

This only happens on FAT32 drives, due to a limitation with FAT32. Files greater than 4GB cannot be created on FAT32 partitions. The only fix is to convert the drive to NTFS, or use another drive that is already NTFS.

To convert a drive to NTFS, click Start -> Run -> cmd, then type convert X: /FS:NTFS, X being the drive's letter you want to convert.

What are labels and what can they be used for?

Labels are a powerful feature in BitTorrent. They can be used for simply labeling your torrents to identify them, or to use for sorting the torrents more easily. For example, you could label your torrents from private trackers as "private", and then click on the Labels column to easily sort all your private torrents. You can select one torrent or more than one to apply a label.
Simply right click on the torrent(s), go to Label, and click "New label..." to add a label, or select an already existing label. This can be done regardless of it a torrent already had a label.
To remove a label from a torrent, right click the torrent, Labels -> Remove Label.
Unused labels are automatically removed from the list.

If you would like labels that never disappear, you can add persistent labels in Advanced -> User Interface.

The benefit of normal and persistent labels is that they can be used in tandem with "Move completed downloads to" in the Folders section. The label would be used as a subdirectory to place the completed download in.

What do all those colors in the Pieces tab mean?
  • Dark blue means the data is downloaded and written to disk.
  • Medium blue means the data is downloaded but still in the cache.
  • Light blue means the data has been requested from one peer.
  • Green means the data has been requested from multiple peers
When I try to download a torrent I get an error message saying: "Torrent got exeption: BTL.BTFailure : Filename path exceeds platformlimit."

What's happening is there is a path name limitation in Windows. If the torrent has a long file name, the combination of that file name and the directory you are saving the files to may result in a total path name that is too long for Windows.

Try saving both the incompleted file and the finisihed file on the top level of the drive, like at C. Files names saved at C would just be C:/filename, so the path name would be shortened as much as possible.

What is that magnifying glass and box for?

That is BitTorrent's search bar. Click on the magnifying glass to select what site you want to search on, then type what you want to search for and press enter. This will launch your browser. You can add and remove sites to the list by going to Advanced -> User Interface and editing the Search Engines box.

What does Force Start (Downloading [F] / Seeding [F] ) do?

Force Start is a way to start torrents to bypass queue settings and seeding priority settings. It can also be used to make torrents keep running/start in "Turn Off" hours with the scheduler. For example, if you set it to run 2 torrents max, but wanted to run a third, you could Force Start the third one. Forced torrents do not count towards the queue settings. Or, if you had torrents set to stop at 150% share ratio, but wanted one to keep going, you could Force Start it and it would not stop at 150%.

You can make a torrent Force Start by right clicking on it, and choosing Force Start. This works regardless of it the torrent is stopped, queued, or started. To set it back to normal mode, right click on it and choose Start.

What is the Logger tab and what does it do?

The logger tab has useful information. When logging is disabled, it shows hash fails and on which torrent they happened, as well UPnP status messages. Right click and you can turn on Log Peer Traffic (Verbose has additional information), though this is generally useless and a slight waste of resources, so it's not recommended to turn on unless you're troubleshooting. Dump DHT Buckets/Tracked give detailed information about DHT.

You can log to a file by right clicking -> Log to file. Be sure to specify the FULL SAVE PATH, including the filename. This will not save the buffer, only lines that showed up after you set it. To stop logging, go back to Log to file and hit OK with nothing written in the box.

What do all those flags in the Flags column mean?
  • D = Currently downloading (interested and not choked)
  • d = Your client wants to download, but peer doesn't want to send (interested and choked)
  • U = Currently uploading (interested and not choked)
  • u = Peer wants your client to upload, but your client doesn't want to (interested and choked)
  • O = Optimistic unchoke
  • S = Peer is snubbed
  • I = Peer is an incoming connection
  • K = Peer is unchoking your client, but your client is not interested
  • ? = Your client unchoked the peer but the peer is not interested
  • X = Peer was included in peerlists obtained through Peer Exchange (PEX)
  • H = Peer was obtained through DHT.
  • E = Peer is using Protocol Encryption (all traffic)
  • e = Peer is using Protocol Encryption (handshake)
  • L = Peer is local (discovered through network broadcast, or in reserved local IP ranges)
I get "Error: Data Error (cyclic redundancy check)" and my torrent halts.

This is not a BitTorrent error, but instead an error reported by your hard drive. It means that your HDD was unable to read or write the data because the sectors are faulty or starting to die, which may be a sign of future disk corruption. Running chkdsk might help, but you may need stronger recovery tools.

What do the colors in the files tab mean?

Blue means the data has been written to disk. Green means the piece is being actively downloaded.