Try a clean boot (Vista and W7) http://support.microsoft.com/kb/929135 (except for MSE). If the problem goes away then it’s just a matter of tracking down the culprit causing the problem. Follow the procedures in the article. Once found, delete, remove, deactivate, or uninstall it. Once done be sure to reset your system back to normal status as explained in the procedures. If the problem occurs in clean mode then just restore the system to normal status and reboot – this solution is not going to work. If using XP, seehttp://support.microsoft.com/kb/310353 andhttp://support.microsoft.com/kb/316434.