Kirk,
I ran across this problem just the other day as well. I was also using PM (v4.5.3) on a laptop running XP and AVG at the time. I am unaware of any files that AVG may have removed, and its logs do not seem to indicate that any have been removed. Is there a specific file that I should check for?
I did retry starting PM, and on the third attempt it did load, so I did not reinstall. I have not had the problem again, although I've only used the laptop a few times since then. If this is a potential problem I might run into in the future, I will probably need to always keep a copy of the latest PM setup program on the laptop, as when I encountered this problem I was at an event and without Internet access.
-Ian