PC starts up then shuts down

My old PC is an Advent Pentium3 running XP Home.

Problem is that it shuts down immediately it has completed a normal startup.

When it completes it's startup everything appears normal - desktop, startup programmes etc. But even if I do nothing, it immediately begins shutting down as if I'd done Start - shutdown.

It does exactly the same if started in safe mode.

I have also tried starting it in last known good configuration - same result.

Any suggestions as to problem or cure would be appreciated.

Cheers all,
Lee

 

I'd try 2 things first.

Hardware: maybe PSU problem. If you have extra power supply, try replacing it.
Virus?: there was an old virus that did this. I believe it used simple batch file and used "shutdown" command. as soon as your computer boots up, go to start-run and type: SHUTDOWN -a

Try these and let me know.

 

I've found the problem!

More by luck than judgement or skill. It appears that one of the serial ports must be faulty. I knocked out a serial port lead while reaching behind the PC... and it started up OK and didn't shut down.

Only realised the serial lead was out when I tried to use the application.

Plugged it back in and the PC began to shut down immediately.

Let it boot up again and put the serial lead in the other serial port and the PC stayed working.

So it looks like a problem with the serial port!

Thanks anyway

Lee