MacBook Pro turns off immediately after startup chime

[MoodyM]

I booted into Windows 7 on my boot camp partition and was about to play Dirt 3 for the 1st time.* I was in the options menu of the game and my MacBook Pro just shut down/turned off instantly.
*
I turned back on, holding in Option so I could boot into Windows again, but the computer just turned off immediately after the startup chime.* I turned on again, this time I didn't hold in Option, so I could boot into OS X (my default startup volume) and the same thing happened - MBP shut down immediately after the startup chime.* I tried again, same thing.* I tried again, and this time it booted fine into OS X, and all seems ok.
*
I tried rebooting into Windows again, and it seems fine now too.

Any idea what's going on?

 

[deadwulfe]

Are you, by chance, using a Seagate Momentus XT Hybrid drive?

 

[MoodyM]

No, the internal HD is a Toshiba MK1059GSM 1TB drive I fitted myself.

Thing is, I tried playing DiRT 3 again, same thing happened, then the MBP would turn off straight after the chime again for about 3 attempts, then booted fine.

I went into Windows again and played a different game (Shift 2 Unleashed) and all is fine.

It seems DiRT 3 was the problem...