This may not be the same issue but...

My roomate just got a new PC and it was powering off randomly (in Windows, during boot up, while idling, or in a game)... we checked CPU, RAM, Hard Drive, OS, blah blah... today we swapped power supplies with another machine, and the other machine got the power-offs instead.

So if you got an extra power supply around, swap em and see if you can either A) not get the error anymore or B) get the same problem on another machine via the power supply swap.