What OS are you using?
If you have XP schedule a boot-time scam from within avast.
What avast! version and VPS file (virus database) number, e.g. 0436-4 (see about avast!)
What was the virus name?
What actions have you taken to try and resolve the problem?
Did you receive and error mesages, if so what were they?
The fact that nothing comes up on google makes it more suspicious to me.
You could also check the offending/suspect file at: Jotti - Multi engine on-line virus scanner if any other scanners here detect them it is less likely to be a false positive.