There are other things that can trigger the shutdown or standby also. #1 being an overheat situation. Check to make sure that the vents are open on it and that nothing is blocking the vents or any buildup of dust bunnies on the chips or anything. That out of the way, there are other things that trigger the shutdowns like screen savers, periods of inactivity or the one that i discovered recently of running on battery power or not running on battery power. Plus, I never use screen savers.