This happened when my X5 had 3000 miles on it had to go in the first time re programed the gearbox software which was ok for 300 miles then did it again this time replaced a electronic box which conrols the gearbox! The reason the car goes into fail safe mode is to protect the car as it thinks it has a fault,But if you leave it 30 mins the problem would go away.What was wrong with mine was that the X5 belived it gearboxs was over heating.