Odd startup

I've just built a rig and there seems to be a strange start up problem i was wondering if anyone knew what is causing it.

When i start up the system it starts turning everything on and you start to hear the spinning of the hard drive and fans and everything else.

Now after 10 seconds or so the system will shut itself down.

It will then power itself back on after 3 seconds and boot up perfectly and everything on the system seems to work fine.

I'm running Prime95 at the moment and it's not crashed or turned off yet.

Anyone have any clues?

Spec:

Intel Core 2 Duo E6750
Abit IP-35
450W Corsair VX
2GB Corsair TwinX
8800GTS

Thanks

This may help
http://forum.uabit.com/showthread.php?t=127743

Thanks mate, that seems to have sorted it out!