I WAS TRAVELING ON AN INTERSTATE HIGHWAY IN THE MIDDLE LANE AT 65-70 MPH WITH CRUISE CONTROL SET WHEN TRAFFIC SLOWED DOWN SUDDENLY. MY FIRST REACTION IN THIS CASE IS TO PULL THE SPEED CONTROL LEVER TOWARDS ME TO DISENGAGE IT AND TAKE MANUAL CONTROL OF THE CAR TO SLOW DOWN BY BRAKING OR DOWNSHIFTING, AS PER USUAL PROCEDURE. IN THIS CASE THROTTLE FAILED TO DECELERATE AFTER SEVERAL ATTEMPTS, UPON WHICH I THEN REPEATEDLY STAMPED THE BRAKE PEDAL, WHICH WAS ALSO UNRESPONSIVE (DID NOT CANCEL ACCELERATION OR SLOW THE VEHICLE). OUT OF OPTIONS, I SWERVED TO THE LEFT TO AVOID THE TRACTOR-TRAILER DIRECTLY IN FRONT OF ME AND REAR ENDED A MOVING VEHICLE IN THE LEFT LANE. WITH BRAKES STILL UNRESPONSIVE, I MANAGED TO CUT ACROSS TO THE SHOULDER WHERE I WAS ABLE TO STOP THE CAR BY DOWNSHIFTING IN ADDITION TO USING THE HANDBRAKE. *TR