Avast is a multi-layered system, that I replaced AVG 9 with, on my PC w/HDTV board. Why? because it interfered with my HDTV board...
Avast is complicated to set up, and may not work on some PC's.

If I were you tho, and If I didn't have the TV board/Option, I would completely UNINSTALL Avast, and try the FREE version of AVG 9, that I have on my other computer. It's hard to beat for simplicity, and being trouble free, with it's auto. updates, Etc.

Terry M.