I WAS SETTING THE HOMELINK MIRROR ON MY CAR TO RECOGNIZE A PARTICULAR GARAGE DOOR OPENER. THE MIRROR IS POWERED SO I NEEDED TO LEAVE THE CAR IDLING. I PUT THE CAR IN NEUTRAL AND BEGAN THE PROGRAMMING PROCESS. THE LAST STEP IN THE PROCESS IS TO ENGAGE THE GARAGE DOOR OPENER FROM THE MOTOR HEAD. TO PREPARE TO DO THIS, I EXITED THE CAR AND MOVED ON FOOT INTO THE GARAGE TO LOOK FOR A STEP LADDER. AS I WAS SEARCHING FOR A STEP LADDER AND AFTER A PERIOD OF AT LEAST ONE FULL MINUTE, THE AUTOMATIC TRANSMISSION SLIPPED INTO "DRIVE" AT WHICH POINT THE UNOCCUPIED CAR DROVE INTO THE GARAGE AND HIT THE REAR WALL. *TR