applications close on scrolling quickly in Xp. no viruses or spyware PC is scanned. Please help?

P4 1.5Ghz 512 RAM, Xp SP2
Problem with all browsers (IE6, firefox, opera)

Answers:
Best Answer - Chosen by Asker

Hmmmm
Let us try the following.
1- Clear history and cookies
2- Delete temporary internet files
Both 1 and 2 are in Internet options from Control panel
3- Restart computer and try again
4- Mark me as best answer if the problem goes with the wind
5- Check for antivirus, you need one