if it keeps restarting giving yo a message that you need to restart it sounds like a kernel panic. the following article tells how to trouble shoot this:
also try smc reset, the following article tells how to do that as well:
you can also run the apple hardware test to see if it's a hardware issue, this article is for that:
based on the results of following these articles you may need to take in for repair. good luck
Okay, so I've attempted to run the hardware diagnostics first because I was going to go out and just let it run for a while and wait untill I've come back.
I got the laptop to shutdown, held 'd' for the diagnostics. Selected English from the language drop down but when I press enter it will just crash, I can no longer move the curser and it will sit there untill I force it off. I've tried this twice now with the same outcome.
Looks like it's a trip to Apple with it, I'll be going in on Thursday, I've made an appointment anyway.