I am not familiar with that particular tuneup utility, but I have always been wary of what these tools were doing in general. I know how to clean up my own space, Windows 7 now defrags in the background without affecting performance, and I want no software touching my performance settings. The only thing I run once in a while is EasyCleaner, a free utility to eliminate bad registry errors, and to be honest, I’m not sure this is really necessary any more in Windows 7, but it seems to do no harm.
Anyway, sounds like you’re getting it sorted out. Maybe someone who knows this AVG tool will comment.
Good luck.