About a week back I was at my PC reading the news and playing Football Manager. Then for no reason my PC seemed to shut down and the monitor went into stand by. I thought I had somehow lost power but the PC was still running, the front LED was still on and the internal fans where still on.

I turned the PC off and tried to start it up as normal but I only got a partial start up. DVD/CD and CDR drives would spin up as normal but then stop and no response from monitor or keyboard/mouse.

I tried a couple of things myself, opened up the case and checked all the wiring and connections, replaced the mother board battery and dusted. No change (At this point I was thinking PSU/MOBO/HD problem). Randomly I tried a DVD but nothing happened so I took it out and to my surprise the PC restarted and booted up as normal.

I started using my PC as normal and tested out all the programs I could think of and did Virus/Ad ware scans which found nothing. So I gave Football Manager another go and my PC dropped dead with all the same problem as before. Again, I tried a DVD and the PC rebooted.

So this time I made an effort to crash the PC by starting up Football Manager I played around for a good 3-4 hours and then the PC crashed, I put a DVD in got no response.

Frustrated I just left my PC on and about an hour later it started up completely at random without me doing anything. So what can it be? It sounds like a hardware problem to me but why does it only happen when I'm playing Football Manager?

Specs.

CPU - Intel Pentium 4 2.66 GHz

BIOS - Phoenix-Award BIOS. Press the F1 key to enter.

Motherboard - Microstar MS-6579

Memory - 512 MB DDR RAM - PC2100

Hard Drive - 80GB Maxtor DiamondMax 4D080H4

CD Drive - 40x 24x 12x Mitsumi 48X9TE CDRW
16x Samsung SD-616F DVD-ROM

Video Card - nVidia Geforce 4 MX440 128MB

Well i know that if i play intensive gaves like far cry alot on my machine, it randomly powers off. I belive that is due to a combination of factors. A: the pc overheating and B: the components drawing too much power

OK, so it isn't playing games that cause the problem. I left my PC this morning and returned to find it crashed. I turned it off and back on again, left it and when I came back to it 2 hours or so later it had rebooted.

PSU? MOBO? Overheating? I'm at a loss to explain it.

Go into control panel -> System -> Advanced tab -> Startup and Recovery button.

If "automatically restart" is checked then uncheck it. Next time it crashes you should get a full diagnostic error message. Post it here.