Edit: I have somehow missed reading several pages of this thread, having read only to the bottom of the first page, so the information I posted before here was kind of off topic. I apologize.
If you are able to get a file on disk that's known malware, even though Avast is supposed to be able to detect it, then you are right for posting it as an issue here.
That said, there is the capability to schedule thorough scans for a reason...
-Noel