Skyrim crashing

[kustomize]

My Skyrim has been crashing my computer (powers off, I have to switch it on again) every time I try to play the game. These crashes come randomly, i.e. on the title menu, or just playing after 5 minutes. I do not think this is an overheating problem.

 

This is not a CTD crash, my computer switches off completely.

 

What I've done so far;

-Updated Skyrim to the latest version

-Configured my system sound settings, updated the sound driver

-I have the latest drivers for my GPU

-Used the "4gb Patch" - enabled my Skyrim to use 4gb

-My Windows is up to date

-Fixed registries

-No mods installed

 

My current setup is;

• 
   
  
• Intel Core2 Duo 2.4GHz
  
• 8GB Ram
  
• nVidia GF 9600m GT
  
• Windows 7 Ultimate 64-bit
  

 

--Also as a side note, I'm using the early 2009 Macbook Pro if that matters.

Any tips, tricks highly appreciated.