For Dell XPS 12, running Windows 8.1. Sometimes I "shut down" my computer, but after several minutes it restarts on its own. When it restarts, the hard disk is operating and the keyboard lights up, but the screen is blank and the keyboard is unresponsive. I have to do a hard re-start by holding down the power button for several seconds. Unfortunately, this has happened several times when I have put the laptop into a computer bag, and I when I get the computer out it is really, really hot from being on inside the bag. Any tips on how to solve this one?