What i meant, was that you should open the task manager, and then click on the processes tab. This will tell you how much cpu and memory resources are being used by each program. This should let you know what is going on. If you are using netscape or mozilla based browsers, your cpu load my be high if you begin to scroll a page that hasnt finished loading. I dont know why this happens, but i have experienced it mysefl.
good luck.
EDIT : duh, you are using ie, not mozilla . . . my bad. However, it might not be a bad idea to download the latest release of mozilla - it has more features than ie, including popup blocking. That could at least narrow down your search for problems.