Ok, I left if off for about 4 hours, started it again and within 2 minutes it did it. It is on a stand so it has ventilation. I don't think it is over heating.
It is a sony GR150K.
And to complicate things even more! About two years ago, it was in a car accident with me
My insurance company took it and decided it was fixible. They replaced the CD drive and snapped it back together.
About six months or so after that every time I would walk around, or pick it up it would do this. I finally got them to agree to look at it again and they tested it for 2 or three weeks. They said that it wouldn't do it for them - well it finally did and they said it was a memory issue. They replaced the memory and sent it back to me. It has been fine since then - until about a month ago
If I have any warrenty left - it won't cover it because of the accident, and the insurance won't do anything else because they are sticking to their claim that they fixed everything caused by the accident!