I have read several posts about PCs and laptops shutting down after upgrading to Windows 7. I think the problem lies with the OS itself. I am having a problem with my Dell laptop too. I could not play any games with it. If I do play games, the laptop will shut down within five minutes and I will lose all data.
The problem is that after upgrading to Windows 7, the fan keeps switching on and spinning quite loudly as compared to before Windows 7 days (it was on Windows Vista previously). Microsoft....Help!!!
Update: 21/02/2010 - Finally solved the problem by wiping out the existing OS (Windows 7 Pro 64 bit) and install the laptop with Vista 64 bit, then wipe the hard drive again and reinstall Windows 7 Pro 64 bit. After doing that, I started updating the Windows OS. When I asked me to restart, I will just restart the laptop. After finishing with it, I would only then install programmes on the laptop.
It's working fine now without any shutdown. If you ask me what was the cause of it, I would not be able to tell you but the problem is now solved. Mind you, I do have a laptop stand which will allow more room for more air intake (with the stand lifting the laptop to a 30 degree angle).