I doubt very much it will die in the next few hours of use; I've never seen that happen to mac yet after a shutdown error and knackered macs will show more frequent faults than a oneoff (and even then it might be the less robust nature of the operating and system these days).

As BillE says it sounds like a common-or-garden kernel panic. This can be caused by any number of things but if you're worried I'd start with two procedures: 1) Boot up from your install disc and run a hardware test to check everything's OK and then 2) Run Disc Utility and repair any permissions etc that often get corrupted in the general course of things.

Only if the fault is regular and repeating do you need to worry, and even then it might be a case of a worn-out battery, PRAM needs resetting etc.