Do you have your XP disc?

If so, click on start > run then enter sfc /scannow (*note the space between sfc/)

This will replace any damaged system files, your personal files will be untouched.

Worth a shot...i believe i did that already i replaced the hard drive and re installed windows. is re format different??Have you tried resetting IE?

http://support.microsoft.com/kb/923737

(I know your problem is affecting FIREFOX aswell but it can't hurt to try. Reset then try IE)

Also make sure you have all critical updates from Microsoft updates...

See if theres any change...i still have the same problem. i am afraid i MAY have to take it somewhere to have it repaired. but i know they will run all the spyware and ad ware scanners and the will have no luck. just like i have. and then they will reload windows. all of witch i have already done and they will charge me $200 dollars and i will still have the same problem.As Broni advised, format the HD then reinstall windows from scratch.

Here's a guide:

http://lifehacker.com/software/windows/geek-to-live-how-to-format-your-hard-drive-and-install-windows-xp-from-scratch-157578.php

Good luck & sorry I couldn't be more help...sorry i have been away/
i formated the hard drive and i have the same problem as before. it acts up before i even log ono the internet.