What is the infected file name, where was it found e.g. (C:\windows\system32\infected-file-name.xxx) ?
Check the avast! Log Viewer (right click the avast 'a' icon), Warning section, this contains information on all avast detections. C:\Program Files\Alwil Software\Avast4\ashLogV.exe
- Or check the source file using notepad C:\Program Files\Alwil Software\Avast4\DATA\log\Warning.log and copy and paste the entry.
If you have the URL to the VT Results page, you could post that.
If it is indeed a false positive (and it seems so), send the sample to virus@avast.com zipped and password protected with the password in email body, a link to this topic might help and false positive/undetected malware in the subject.
- Or you can send it from the Infected Files section of the chest (select the file, right click, email to Alwil Software). It will be uploaded (not actually emailed) to avast when the next avast auto (or manual) update is done.