Rebooting PC

System reboots with 'Serious Error'

A user I support is experiencing frequent system reboots each night. When he comes in in the morning, he receives a message stating that a 'Serious Error' has occurred. There's a long string of info below, so I'll say thanks in advance for any help anyone can offer on the issue. Lordhowe Below...

Computer continually reboots

I reformatted a hard drive and reinstalled XP Pro; I was able to install Office and antivirus. But then for no apparent reason, the computer reboots immediately after login. I have no idea whether this is a hardware or a software problem. Does anyone have any insights? Thanks