Cant Boot XP, Can Restart

I'm having a really wierd problem with my PC - I can't boot from cold, but I can boot if the system is restarting.
i.e.
If I shutdown, wait a few minutes, then turn on the PC, Windows XP gets to the Splash screen (before the login) then after a few seconds it reboots.
It then continues this loop for as long as I leave the PC on.

If I boot into Linux (gOS) first, then restart the PC from there, XP starts fine.
Equally, if XP is already running I can restart with no problem.

Any ideas what could be causing this?

that is very strange. I would say (based on no information at all but a wild hunch)
you have more than one hard drive in the system, and both of them have a boot sector. You are cold-booting from c drive into linux and this works but you can't cold boot into xp this way because you've reinstalled xp in the past and you have more than one xp configuration. However linux's boot loader is configured to boot the correct one and obviously if you exit and restart xp already knows where it is so it will boot fine. I suggest you check your bios to see which drive is booting, and pay attention to what the boot loader launches and see if it matches the drive path to the xp install you use.

@agmorgan

I am having the same problem with my pc! Although for me it doesn't happen all the time. Do you receive error messages from within Windows saying it encountered a fatal error? I get messages like that.