Computer stuck at loading screen (Windows Vista)

My friend's computer (which I'm using) is stuck at loading screen. It's a Toshiba Satellite 64-bit with Windows Vista. I told him to format but he refuses because he doesn't want to lose stuff he has.

I am currently on the Safe Mode with Networking, so anything you need me to do I can do from here, except install programs.

I tried to do a virus scan with avast!, but the computer shut down. Tried again, and it shut down again. It shut down when it was about 70% done, and it had found 18 infected files. I did another scan, but this time I stopped it when it had 11 infected files and moved them to chest. And now when I do the scan it shuts down on 4%.

Can this be the cause of my problem? Or is it another thing? Solutions?
 
The Wife ACER 64-bit Windows 7 HPM on it did the same think I just had wipe it out and gave it Ultimate 7 64-bit and she couldn't be happier on her 17.3 laptop.
 
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