Hi there. Whenever I put my PC on stand by it restarts it's self after 20 seconds.
Why would this be happening & how do I stop it?

It's nothing to do with my optical mouse. Ive tested putting it on stand by about 10 times & it starts it's self every time after 20 seconds.

It's only started doing this in the last few days.

Any help much appreciated

A few links to browse with the standard issues:

Windows XP restarts unexpectedly or restarts when you shut down the computer


Windows XP restarts when you try to shut down your computer


Windows XP Shutdown Troubleshooter

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Do you have any other USB devices connected? I had this problem a while back on my old motherboard, and it turned out that when I standbyed the computer, after about 10 seconds the USB device went into standby mode, and the change in power state woke up the machine.
I think it was my USB phone or sommin, but it was same with my iPod.

If you go into the BIOS of your machine, you can usually specify if USB devices wake the machine up or not.

Hope this helps,
Paul