So to all you 360 owners, what gives, it happened on the same game 'moto gp 06'.
Whether its a coincidence or not, I dont know, after the 2nd crash/lock up, the unit would not respond to the power button, I had to unplug it for a few mins from the wall, plug it back in, and it worked fine.
I am thinking it was an overheating problem, It was in a cupboard in my ent cab, and I had the door closed, so there was an exteme amount of heat generated from the unit, I had been playing maybe 4-5 hrs straight

when this happened, since then I have left the door of the cabinet wide open, and did not play a 'disc' game since that last lock up, I decided to join x-box live soon after the last lock up and D/L some free demo.
The system was almost cold to the touch after cooling down and running the machine only on xbox live, playing demos I had downloaded did not increase the temp much at all, so maybe keeping the door open did the trick, or I might need to move the box to one side of the tv.
I had owned a orig xbox for 18 mths in exactly the same location in my ent cab as my 360, and it got warm, but never HOT, I hope this is the solution, I have read horror storys of ppls machines locking up with no warning, and getting the screen of death, I had the flashing red lights, but did not pay attention to what code it was until I had read up on it
Gav