At first I thought you might have a virus that attacks your RPC. There are
several around that will do that. But then you mention that the machine did
stay up for 6 hours, and that leads me to think that perhaps your machine is
overheating because of a bad CPU fan. Most BIOS have a setting for just such
an occurrence. When a CPU overheats, the machine will shut down
automatically to prevent damage to the processor. You can generally tell by
the sound if the fan is failing. It will change pitch as it speeds up and
down and will sound a bit grindy.

If you have a tower, it is a relatively simple operation to replace the fan.
If its the type that lays flat, you will need to how to open the thing up.
That can sometimes be a challenge.

I recently had this happen to one of the machines I care for just a couple
of weeks ago. Installed a new fan and it now runs fine again.

George Emond
MS Beta Program Test Member

wrote in message
oups.com...
This started happening to me last nigiht. The computer just suddenly
goes off and when I switch it back on it will stay on for about half
an hour then go off again. I left it on while I was out today (about 6
hours) and it was still on when I came home, but it started again
about two hours later.