PULLING INTO A PARKING SPACE AT KAISER HOSPITAL AS I HIT THE BRAKE THE CAR UNEXPECTEDLY ACCELERATED. THE CAR SPED FORWARD WHILE MY FOOT WAS STILL ON THE BRAKE. I HIT A TREE CAUSING DAMAGE TO THE LEFT FRONT AREA OF THE CAR (LIGHTS, FENDER, BUMPER) HAD CAR REPAIRED. AT THE TIME I THOUGHT THAT I HAD ACCIDENTALLY HIT THE GAS PEDAL;HOWEVER, ONE MONTH LATER WHILE APPROACHING AN INTERSECTION, AS I STOPPED, THE SAME THING HAPPENED. LUCKILY NO CAR OR PEDESTRIAN WAS IN THE INTERSECTION. I WAS ABLE TO STOP THE CAR BY SHIFTING INTO PARK. TOOK THE CAR TO MY MECHANIC. HE WAS UNABLE TO REPLICATE THE PROBLEM. SINCE THIS UNEXPECTED ACCELERATION OCCURRED IN THE SAME WAY (COMING TO A STOP WITH FOOT ON BRAKE AND GEAR-SHIFT IN DRIVE) , IN A FIVE WEEK PERIOD, IT COULD BE A TRANSMISSION OR ACCELERATER PROBLEM. I NO LONGER FEEL CONFIDENT DRIVING THE CAR AND CONSIDER IT UNSAFE.