ERROR #131 (0x85100083) File Corrupt

Hello Davocnavo,

The repair utility should be working properly now. Please start with that tool, which should be found in the Start menu folder for World of Warcraft as World of Warcraft - Repair.

Here is the support page on this error as well:
http://us.blizzard.com/support/article.xml?articleId=21026&searchQuery=error%20131&pageNumber=1

If the files themselves don't seem to be corrupt, then we need to know why they're being read as such. Memory issues, other software, and viruses would be some things to come to mind.

Memory Tests
We are tentatively recommending users try memory scan utilities such as the Windows Memory Diagnostic, available directly from Microsoft:
http://oca.microsoft.com/en/windiag.asp

Here are a couple alternative scanners that are easier to use, but may be somewhat less reliable:
http://www.memtest86.com/
http://hcidesign.com/memtest/

If you're using Windows Vista, it has a built-in memory test: http://us.blizzard.com/support/article/21056

Virus Scans
Please try Trojan Remover from: http://www.simplysup.com/tremover/download.html

We have received reports that Fix Wareout may also be able to detect and remove malware. You may download this security program from: http://downloads.subratam.org/Fixwareout.exe

Another good anti-virus program to try is Kaspersky Anti-Virus: http://www.kapersky.com

For additional information and links to some anti-virus software please visit our Computer Security page:
http://www.blizzard.com/support/wow/?id=asi0462p

Selective Startup
Please startup your computer with a Selective Startup through your System Configuration Utility. To do this, please go through the following steps:

-Click on Start, then Run (or for Windows Vista, hold down the Windows key and press R)
-Type in "msconfig" and press Enter
-On the General tab, click on third option down (Selective Startup)
-Then unfill the fourth box below (Load Startup Items)
-Next, in the Services tab, check "Hide All Microsoft Services"
-Then click on Disable All
-Click on OK and restart your system

After your computer restarts, click on Do not show this message when Windows starts up, then OK.

Remember that you may re-select Normal Startup afterwards to remove the changes.

I would imagine not, but that is not one of our official mirror sites, so you can never tell.

This page has links to some of our supported downloads and instructions on what to do with them.
http://www.1up.com/do/newsStory?cId=3170631

Since you already have the patch installed however, there will need to be something else done to try removing it.

In order to revert the game to a previous version, please try the following steps:

1. Open your World of Warcraft directory (This is commonly located at C:\Program files\World of Warcraft)
2. Open the folder called "Data"
3. Delete the Patch.MPQ file
4. Run the repair.exe utility found in the World of Warcraft directory
5. Click the button "Reset and Check Files"
6. The repair utility will say, "World of Warcraft is seriously damaged and will need to be reverted to an earlier version. After it has been reverted you may need to patch up to continue playing."
7. Once the repair utility has completed, you will need to reapply the patch to enter the game.