A couple of days ago i switch to Windows 8.1. All of a sudden i'm doing something and it just restarts. It happens once or twice during the day. It then wont see my hard drive and i have to hold the power button to turn it off and then it boots right into windows. This has never happened with Windows 7 at all. Did something happen when i went to install it? Should i reinstall windows 8.1 or go back to windows 7? I've tried to run the repair tool from the windows 8.1 disc and said it couldn't be repaired.