turning off on it's own

I was operating on battery power the other day and then all of a sudden my MBP just turned it's self off, didn't shutdown, just flicked off. I tried turning it back on and halfway through the start up it just turned off again. I connected the power supply and everything was fine but then took the power supply out and once again it flicked off!!!

anyone got any ideas?

There has been a lot of discussion on this topic, both on this forum and on the Internet at large. If you search for this issue you should find lots of information. Basically, in the MBP the batteries are being blamed. How old is your machine? Your best bet is to take it into an Apple store or call AppleCare and you'll get a new battery.