WAS PULLING OUT OF PARKING LOT WHEN VEHICLE JERKED HARD IN DRIVER'S HAND. LOST CONTROL & HIT A CURB. TOWED VEHICLE TO DEALERSHIP & MECHANIC DISCOVERED THAT TENSIONER WHEEL BROKE, AND SERPENTINE BELT FELL OFF. ALSO, MOUNTS TO SIDE OF MOTOR & SHAFT HAD BROKEN IN HALF. TENSIONER WHEEL NEEDED TO BE REPLACED. *AK