Just don't let it go to sleep. Right click on your desk top, very bottom, personalize, screen saver, under power management, change the power settings. Change when the computer goes to sleep, select never. Mine was doing the same thing. I just don't let it go to sleep anymore, problem solved, for me anyway.
Vista is still a piece of shit for somethings. Not thrilled with it. Did you turn off user account control too, get rid of those blasted pop-ups every time you want to do something, highly recommend doing that.