Prevent your system going to sleep with simulated key presses
Platform: Windows 8 compatible, Windows Vista 64-bit, Windows 7, Windows 7 64-bit, Windows Vista, Windows XP
Caffeine is a simple free tool that prevents your PC sleeping or screensaver activating. The program simulates a keypress every 59 seconds, fooling your machine into thinking you're still using it, stopping it shutting down.
Simply click the icon in the system tray and you can control how you'd like it to work. Theres no need to run it permanently, either. Right click the icon and you can use it for a couple of hour's or however long you need to.
Other options include which keypress is simulated, and how often you'd like it to be repeated. You can also prevent your sytem going to sleep, but still allow the screensaver to start.