My computer, after receiving a windows security update, will not reboot to windows except in safe mode. When I restart windows it gets to the bar at the bottom of the screen and c microsoft corporation page then the screen goes black. When the post pages are loading there are letters all over the screen. I tried system restore as far back as I could, that didn't work. I tried reloading windows vista, that was unsuccessful. I do not get any options to repair windows at any time. I have Vista home premium. Thanks