Have you tried the microsoft site?
http://support.microsoft.com/
they have a help line and knowledge base plus tech chat.
I know though that when I had a smaller hard drive and 256 mem. I had a lot of similar probs though. XP takes a fair bit and If you have lots of stuff on your com maybe that's the problem - not that i'm an expert!!
since I got a bigger HD and more memory I've had no problem at all
Not with AOL are you? lots of conflicts reported with them and XP!