I have a problem with fullscreen games such as Roller Coaster Tycoon 3, Microsoft Flight Simulator, and Microsoft Combat Flight Simulator 2 crashing after 15 min of gameplay. Combat Sim 2 switches between fullscreen flight mode and window style menus, so it does not crash unless i have been flying for 15 straight minutes. When these games crash, my monitor just goes black and my computer acts as if it is going into a screensaver mode. I have disabled all screensavers and it still happens. I have an ATI Radeon Graphics Accelerator installed and I have checked in BIOS that AGP was set. I have searched multiple forums for a solution to this problem, but have yet to figure out the problem. ANY help would be appreciated.