Event 41, Kernel-Power

Hi, I Build this PC in April 2012, so its about 8 months old. It did run perfectly without any serious errors until now. Now i experience the system hanging, so i can't move the mouse anymore, and pushing the "Caps Lock" or the "Scroll Lock" on the Keyboard don't turn on the respective lights on it, so i guess it's a hard hang. In the Event Viewer i see a "Event 41, Kernel-Power" critical...