xp computer restarting

[excalibur3]

I have a custom built computer that I use to run a microscope. I have had it for about 9 months without a problem but the last two nights it has restarted so that when I came in instead of scanning, it was on the logon screen. It runs windows xp sp1 and the only thing that I've changed is that I installed an updated version of a program. Would that cause it to happen? It probably isn't it because it wasn't even running during the night. Anyway, thank you so much for your help.

 

[Markbnj]

Assuming you aren't losing power, then something is faulting. Two suggestions: go to control panel -> system -> advanced tab, then click the Settings button under startup and recovery. In the dialog that pops up uncheck the "automatically restart" option under system failure. After you do this Windows will not reboot itself after a failure, and you will be able to see whatever error messages were popped during the event. Usually it is only serious, or "blue screen" errors that cause an auto-restart.

Second, go to control panel -> administrative tools -> event viewer, and click the System events node in the menu tree on the left. See if there are any recent Stop events. If you find one, report its contents back to us. Same thing if you turn off autorestart and see a blue screen. Copy down what it says and report it here.

 

[pkme2]

You mentioned custom-built.
What's your power supply brand and wattage?
Most unusual computer restarts that we hear about on AT are related a lot to PSUs.
Let's check that first before proceeding to the next step.

 

[NogginBoink]

Originally posted by: pkme2
You mentioned custom-built.
What's your power supply brand and wattage?
Most unusual computer restarts that we hear about on AT are related a lot to PSUs.
Let's check that first before proceeding to the next step.

I don't think that's true. I know lots of people here tend to blame the PSU, but I'm not aware of any BSOD's caused by a faulty PSU.

I've looked at many dumps of Windows crashes, and none of them was ever traced to a faulty PSU.

The vast, vast majority of BSODs are caused by faulty drivers.

 

[Markbnj]

The vast, vast majority of BSODs are caused by faulty drivers.

That's absolutely true. My maxim has always been: it's not the hardware until absolutely everything else is ruled out, unless there is smoke or grape jelly.