Is it normal for Avast to scan over 400 files after you boot and login?
Have you ever thought of how many files Windows itself is using?
Even files in the "\Program Files\" directory like games I haven't played in a long time.
Not playing them doesn't mean they haven't add things to the "load at boottime list". Have a look with [url=http://www.mlin.net/StartupCPL.shtml]StartUp.cpl[/url] at the list.