It is most likely to be a false positive detection, see http://forum.avast.com/index.php?topic=28170.0, same issue.
If it is indeed a false positive, add it to the exclusions lists (Standard Shield, Customize, Advanced, Add and Program Settings, Exclusions) and periodically check it (scan it in the chest), there should still be a copy in the chest even though you restored it to the original location. When it is no longer detected then you can also remove it from the Standard Shield and Program Settings, exclusions.
Send the sample to virus@avast.com zipped and password protected with password in email body and false positive in the subject. Or you can also send it from the the avast chest if there is a copy there (select the file, right click, email to Alwil Software). No need to zip and PW protect when the sample is sent from chest.
