I would normally not have posted this here, but my PC has just returned from the technician after overnight stress tests on all hardware (no errors found), and it has crashed within 2 hours.
The problem is the system completely locks up and I must hold the power button to turn the system off.
I experience this problem randomly when gaming and media playback.
Running Vista home premium SP2 64 bit,
Intel Core 2 Quad CPU Q8200 @ 2.33GHz
4GB RAM
Nvidia GeForce 9600 GS
Any help would be greatly appreciated, thanks.

