My car has actually shut completely off once or twice for no apparent reason... even while driving at a slow crawl. I still haven't figured out the problem, but then again... it only happens like once or twice a year. I just chalk it up as vehicle demon possession.
I must have one too then. At idle warming up mine does that every now and then. Sometimes when I drive then park with the car still on, it'll just die too but that only happened twice.