Vista reboots on its own on an hibernating laptop

[ah]

I am running Vista Business. Around 3am, I was woken up by the
characteristics 4 notes of Vista starting. I got up and opened my laptop.
The screen was asking for my password. It had rebooted on its own while
hibernating.

 

[Chuck]

You may have options set that cause the system to come out of hibernation.
IE mouse movement. (Train goes by mouse wiggles, system comes out of
hibernate.
I saw one laptop that did this with a much older version of windows. Turned
out that the space key had been "repaired" causing it to sit slightly high.
When the clamshell was closed, the shift key was partially dipressed. Any
noticable vibration could cause a key down/up signal, re starting the
laptop.