Had my 13" sitting closed on the nightstand and heard what sounded like the fans hitting full speed. Looked at the Air and said to myself, no way.... Was wrong, yes way! Opened the machine, no screen response. Had to hold down the power button to shut down the machine. Does anyone have any idea what would cause this? I've never had it happen before on any of my Mac portables. I looked through some of the logs but that's about like looking under the hood of my car when it will not start. Outside of something obvious, have no idea what I'm looking at.