Game crashes computer

[Cubehead]

Hi, I have a rather annoying problem with NecroVisoN.

When ever I play the game, through Steam or a retail versio, the game crashes randomly(yet nearly after the same time) during gameplay and even takes my computer down with it, so there is no time to see any errors or even a bluescreen

First I tested to reinstal the Steam one, no difference. Then I lend a friends retail copy to test it out, amazingly I could play the first level five times further then with the Steam one, yet this one also did crash, and now, it crashes like the Steam versio.

Both are 1.2 versions of the game.

My computers infos are:
Operating System: Windows XP Professional x64 Edition (5.2, Build 3790) Service Pack 2
Processor: AMD Athlon(tm) 64 X2 Dual Core Processor 5600+ (2 CPUs), ~2.9GHz
Memory: 4094MB RAM
DirectX Version: DirectX 9.0c (4.09.0000.0904)
Card name: ATI Radeon HD 4800 Series
Driver Version: 6.14.0010.6973 (English)
Sound Devices: Sound Blaster X-Fi Xtreme Audio

And yes, I know the game doesn't support 64bit OS, but still. The demo worked just perfectly like a charm, I could play it through on one sit without any trouble.
Plus, King's Bounty: The Legend and Cryostasis works just fine on my computer so I'm rather clueless here

Thank you