Ghosties

I woke up to the sound of my computer re-booting. All by itself. I stayed in bed the first time, but the second, I got up and hit the button and shut it off. I have a desktop, that stays on all the time (except it's off now) and my laptop, which I use all the time. It was the desktop acting up. It was weird, although I think it's happened before. I have found programs I had left running, not running and thought "that's odd" but never really thought too much about it. I watched it re-boot with one eye half open, cringed at the loud windows sound, and dozed back off. then a few minutes later I heard it re-bootng again and turned the power off before it could make the sound again. Then my alarm went off a few minutes later.
I've never heard of a computer re-booting all by itself, except for when you're installing windows. Maybe I have ghosts!