Computer automatically restarts

Hello,
I recently went over to a friends house and tried to repair her computer. It's an Acer, Windows Vista bought 3 or 4 years ago. Anyways, she can't start up her computer without it restarting automatically. I went to do a system restore and it would not let me run the program. Most of the programs are not able to run. I will try the dougknox.com exe fix, but if that doesn't work, any suggestions on what to do? She does not have her original copy of vista, so if we reboot the whole system, Vista can't be restored. Any tips or advice?

Thanks!