I've had this problem for a while now.
Gateway MD2614u (amd64 1.6ghz 1mb L2 cache)
will randomly shut off if I am doing heavy work on the computer, without any warnings on shutdown or start-up.
This problem did NOT occur in Windows 7, but has occurred in both Ubuntu 10.04 and Windows XP.
I have downloaded lm-sensors and have done some tests and I'm getting an average temperature of 74c and a high temperature of 92c+ (it shuts down at 100c+).
As far as I've seen, this isn't even possible?
I see a lot of people saying 50c is bad, and here I am, typing at a supposedly 71c.
What is going on?