m4a files keep degrading

[Canis]

I have a bunch of m4a files on my PC. In retrospect I should have ripped them as mp3s but that's beside the point.

Anyway, after playing perfectly for over a month, the files have started degrading. One song plays fine for the first twenty seconds, then suddenly skips ahead to the second verse and carries on like nothing happened. Several days later, two more songs developed blank spaces in the middle lasting up to around one minute.

I'm running Winamp 5.32 which I believe is the latest version. The music files in question will play in WMP up to the point of error, and then will stop.

What could cause m4a files to lose quality?

[DJ Egg]

An m4a-eating virus? Hard drive corruption/failure?

http://forums.winamp.com/showthread....d=161361#specs

[Canis]

I ran AVG, Adaware, and Spybot, and didn't find any virus or other harmful whatever. I'm not sure how to check for hard drive failure, but I haven't had any other problem.

I've included a Hijackthis log, and here's a link to a zipped file containing one of the damaged m4a files. http://www.sendspace.com/file/st3b98 The skip is at second 17.

[DJ Egg]

O4 - HKLM\..\Run: [winupdates] C:\Program Files\winupdates\winupdates.exe /auto

WORM_VB.AS / Alcra-B worm (Rbot worm variant)

http://www.liutilities.com/products/...ry/winupdates/
http://www.sophos.com/virusinfo/analyses/w32alcrab.html
http://www.trendmicro.com/vinfo/viru..._VB.AS&VSect=T
http://www.castlecops.com/s5642-Winupdates_exe.html
etc etc etc

Fix that startup entry, reboot, and delete the "C:\Program Files\winupdates" folder.

[Canis]

Done and done. I'm rather disappointed that AVG didn't find that, so thank you.

So you think that was the problem with the m4a files?

[DJ Egg]

Yes, because this virus (worm & trojan combined) disables security software and allows a remote attacker undetected access to your computer. Therefore anything's possible, including the ability to modify files.

Also look for these files in your C:\Windows\system32 dir:
cmd.com
netstat.com
ping.com
regedit.com
taskkill.com
tasklist.com
tracert.com

and a "C:\Windows\system32\Complete" folder.

Delete them if found.

(make sure you can view hidden & system files first, via: folder options > view)

Disable then re-enable System Restore, so all hidden backup copies of the worm are also deleted.

[Canis]

I seem to be in a pickle. System32 is hidden despite the fact that I have the appropriate boxes checked or unchecked as the case might be in Folder Options. I tried resetting it with the command prompt (attrib -h -s -r c:\windows\system32) with no change.

Is there another way around this without reinstalling Windows? (Which I might do anyway.)

[DJ Egg]

Don't try to change anything with the actual system32 folder itself, just delete those files and that one subfolder I referenced, if they exist.

Control Panel > Folder Options > View tab

checkmark: show hidden files and folders
uncheck: hide protected operating system files
uncheck: hide extensions for known file types

You can use those command prompt options for the files and folder which need deleting. Save the following text to notepad and save as eg. cleanup.bat

atrrib -h -s -r /S "C:\Program Files\winupdates\*.*"
del /Q /S "C:\Program Files\winupdates\*.*"
atrrib -h -s -r C:\Windows\system32\cmd.com
del /Q C:\Windows\system32\cmd.com
atrrib -h -s -r C:\Windows\system32\netstat.com
del /Q C:\Windows\system32\netstat.com
atrrib -h -s -r C:\Windows\system32\ping.com
del /Q C:\Windows\system32\ping.com
atrrib -h -s -r C:\Windows\system32\regedit.com
del /Q C:\Windows\system32\regedit.com
atrrib -h -s -r C:\Windows\system32\taskkill.com
del /Q C:\Windows\system32\taskkill.com
atrrib -h -s -r C:\Windows\system32\tasklist.com
del /Q C:\Windows\system32\tasklist.com
atrrib -h -s -r C:\Windows\system32\tracert.com
del /Q C:\Windows\system32\tracert.com
atrrib -h -s -r /S "C:\Windows\system32\Complete\*.*"
del /Q /S "C:\Windows\system32\Complete\*.*"
deltree /Y "C:\Windows\system32\Complete"
deltree /Y "C:\Program Files\winupdates"