Here is the error message generated after windows 2000 loads desktop but before you can do anything

"This system is shutting down... save all work and log off... any unsaved work will be loss. This shutdown by NT Authority\ System "

"The system process C:\windows\system32\service.exe terminated unexpectedly with status code 128. The system will now shut down and restart. NT Authority\system "

computer then goes thru a 60 second countdown then shuts down and restarts...cycles over and over

We were in MS Word when the system just shut down.

There was a big outbreak of a virus that caused similar actions a few months ago. What anti-virus software are you running and have you updated it online within the last couple of weeks to detect the latest viruses?

Also, try switching it on and keep pressing F8 (once or twice every second) on the keyboard until it shows a 'Startup Menu'. Select the option to boot into Safe Mode or VGA Mode. When it then loads Windows (it may take a bit longer), does it still reboot?