VEHICLE WAS SHIFTED INTO PARK, BUT RUNNING, IN MY DRIVEWAY. GOT OUT TO LET PASSENGERS OUT. TURNED AROUND TO GET BACK IN AND CAR STARTED DRIVING ITSELF FORWARD, ALMOST HITTING MY CHILD. MANAGED TO JUMP IN AND STOP IT AFTER IT HIT MY HUSBAND'S CAR WITH THE OPEN DRIVER DOOR. THE SHIFTER KNOB HAS MOVED ITSELF INTO THE DRIVE POSITION AND ACTUALLY SHIFTED GEARS WITHOUT THE BRAKE BEING PRESSED.