WHILE DRIVING MY VEHICLE I APPLIED THE BRAKES. THE BRAKE PEDAL BECAME VERY STIFF AND THE VEHICLE WAS NOT SLOWING DOWN. I STEPPED HARDER ON THE BRAKE PEDAL AND THE VEHICLE FINALLY SLOWED DOWN AND CAME TO A COMPLETE STOP. I PULLED OVER THE SIDE OF THE ROAD AND WHEN I PRESSED ON THE BRAKE PEDAL IT WENT TO THE FLOOR SLOWLY AND A HIGH PITCHED SOUND CAME FROM THE ENGINE COMPARTMENT. I TURNED THE ENGINE OFF AND CHECKED THE BRAKE FLUID RESERVOIR TO INSURE THAT I DID NOT HAVE A LEAK. I STARTED THE ENGINE AGAIN AND HEADED TO MY HOME. EVERYTHING WORKED NORMALLY. I TOLD MY WIFE TO NOT USE THE CAR AND TO USE OUR OTHER VEHICLE. I CALLED AHEAD TO THE DEALER FOR SERVICE AND BROUGHT THE VEHICLE IN. WHEN THEY CALLED ME THEY SAID THE BRAKE BOOST HAD FAILED. THEY CHANGED IT AND CHECKED THE BRAKES AND THE VEHICLE WAS WORKING CORRECTLY. I MOVED TO FLORIDA AND THE BRAKE BOOST HAS FAILED AGAIN. THIS IS AFTER APPROXIMATELY 20,000 MILES. THE SAME SYMPTOMS AS THE PREVIOUS FAILURE. THIS IS DISCONCERTING BECAUSE THE REPLACEMENT UNIT FAILED AS WELL LEADING ME TO BELIEVE THERE ARE POTENTIAL DISASTERS OUT THERE. *TR