Re: PC restart at exact moment game begins
Well I followed all your advice, disabling the second CPU didn't do anything so I figured it wasn't SIN having a problem with that. When I disabled Automatic Restart the BSoD showed me that it was a nVidia dll screwing up. So I searched for problems relating to that dll and people had solved it by changing their graphic aperture, but that didn't work for me.
So desparate, I uninstalled all the drivers (which I had done before), the device itself from the OS and then physically removed it from my machine. Restarted to settle everything, put the card back in and reinstalled the drivers. It worked straight away.
With stuff like this no wonder consoles are popular! Thanks for all your help.