I have a 96 Buick Century with a 3100 motor and 45 K miles. A couple of times recently after driving up to a light and coming to a complete stop the car ends up going in reverse all by itself when leaving from the light. The shifter is still in drive when this happens and the car must be shut off put in park, restarted and then drive at which time it goes forward. I have had the car inspected at the local shop but they cannot duplicate the issues as it is sporadic. Any ideas as this is a dangerous issue.