Sudden high-voltage
The system came with a 300W PSU built in, which is what I'm thinking may have caused damage. The CPU was also running at high temps, 60c. It all points that way.
If they're the ones who put it in then surely i can get em to upgrade it? :S I've bought a new 450Watter anyhow.
[edit]
GFK, I've had it about 2 months now. :)
Refund might be problematic as I've installed my new soundcard in there. That was the only time i've been inside and I proceeded with caution then, too.