Sometimes when car is stopped it will slip out of drive gear and you have to restart the car to get it to go again.
Transmission problem on 1996 Oldsmobile Cutlass Ciera
Critical to check and ensure the transmission fluid is full. If it is too low on fluid, it can neutralize and create the symptoms described.
I have to agree with motorplex check the trany fluid make shure it up to at least the cold mark but dont fill passed the hot mark when hot