To know if a file is a false positive, please submit it to
VirusTotal and let us know the result. VirusTotal has a file size limit of 10Mb. You can use
VirScan also.
If it is indeed a false positive, send it in a password protected zip to virus@avast.com. Please, mention in the body of the message why you think it is a false positive and the password used. Thanks.
Are you using Windows XP/Vista?
Can you schedule a boot-time scanning?
Start avast! > Right click the skin > Schedule a boot-time scanning.
Select for scanning archives.
Boot.
If infected files are found, it's safer to send them to Chest instead of deleting them.