My XP was working well until I installed SP1. Thereafter, Windows will not close on it's own. I get an error message "program not responding", in a pop-up, but no information on which program is not responding. The box also has a moving "guage" which counts down time to closing the unresponsive program. But, when this times out, Windows still doesn't close. If I click on the "end now" box, Windows goes into shutdown mode. When I look at Program Manager, nothing is running. I've checked the support page of Microsoft, but can find no information on this issue.