Ok, this virus was just found on my system, Win32:Ciadoor-B [Trj]. It’s infecting my svchost.exe which is a vital system file. Avant says it can’t repair it or anything else, so I was wondering if there was another way to fix it or not.
Hi,
→ this is probably not a system-file, but one that carries the name only…
here you’ll find info & removal instructions for this malware… :
VGREP
(most helpful are usually the links to Trendmicro, symantec & mcafee)
If you can’t resolve the problem on your own, then please read this:
http://forum.avast.com/index.php?board=4;action=display;threadid=5373
& come back here with more info… 
→ Please post the full message by avast, especially the complete PATH/FOLDER/Filename !!