I was playing RIFT on my computer, when suddenly my screen froze. My mouse and keyboard turned off, they were unresponsive and their light turned off. I tried ctrl-alt-delete but of course the keyboard was unresponsive. My sound also cut off. I went on my phone to check my Steam profile, and it said I was offline, so basically everything turned off. My monitor was still showing the picture of the moment in which it froze, and my computer was still on. I held the power button and rebooted, and now it's fine. Everything is working perfectly, and I have no idea what it was because it has never happened before. Does anyone know what the problem could be? I'm running Windows 8 with all updated drivers, if that comes in handy.