I had the same problem yesterday. For hours, Avast, every 10 or 15 minutes, popped up saying that it had blocked Win32:Malware-gen from a windows app which appears to be something Windows based like an app or a widget. But, I can't figure out how to get rid of it... Today, it's not popping up yet so maybe it resolved itself. I wish you could turn off the warning in Avast at least...