Just some help really, I have played Sim City 3000 UK Edition for ages on my PC with Windows 7. And have been doing for ages. However over the past week so my computer will just shut itself off in terms of i'll be on the game one minute and next, thhat's it just turns itself off. So I then take the disc out and turn the PC on and yes it gets past the POST, then yep it switches itself off. Why?