I'm running windows 7 Pro. I was having random freezes and it turned out that my psu had a bad rail. Replaced it with an 850 watt single rail psu. When I try to shut down, it gets to the screen that says shutting down and goes no farther. I then have to use the power button to shutdown. It seems to have started after reinstalling a ghost image and then let Windows update. How can I figure out which update or what program is causing this? Thanks.