XP 100% cpu utilization

I have been having a problem with winxp on my new computer. Every so often applications will start taking up 100% utilization every time you try and use them. Example would be AOL, just logging on would pin it to 100% and the "welcome" sound will go in slo-mo cause cpu is pinned. Other examples paintshop pro, opening a single jpg will pin cpu... The solution is always to reboot until it starts acting up again.... System is a PIII 1.1Ghz, 512ram. Thanks in advance!

 

Tedious solution, but I would start to keep a record of what processes are running when you experience that. Not which application you are starting, but what processes are running at that strange time.

Hopefully a pattern will emerge betwen what runs at that time compared to what runs at normal times.