I am having the same exact problem. I don't want to hijack kevinphilip's thread, but maybe we have the same problem.
This problem started about a week and a half ago. I don't remember installing anything new, but that doesn't mean that I didn't...bad memory. I was having trouble closing tabs in Internet Explorer immediately before this started happening. I would attempt to close a tab and it would freeze the screen for a few minutes. I didn't have a problem closing the whole window.
My specs are:
Windows XP Service Pack 2
Internet Explorer 7
Gateway computer
I can start the computer in safe mode. The FAQ section said that this means it is a software problem. I'm decent with computers, but I have no experience troubleshooting software.
I would be grateful for any help. Let me know if you need more info as well.