Engine shuts off when parking downhill

[ffl]

Sometimes i have to park on a steep road, front downside and back upside. last time the engine shut off 3 times when driving out of the car park. i don't remeber what i was doing when it shut off but i think the car did not move, perhaps it happend when changing from R to D or the other way round, or when doing a reverse hill start. after that i could start the engine again without any problems.

anyone an idea what could be the reason for this? it only happens on this steep road.