WHILE TRAVELING IN A STRAIGHT LINE OF LEFT LANE ON THE PARKWAY AT 50 MPH, I LIGHTLY APPLIED THE BRAKES AND THE REAR OF THE VEHICLE IMMEDIATELY BEGAN TO SWAY UNCONTROLLABLY LEFT AND RIGHT. THE BRAKES WERE LOCKED CAUSING THE VEHICLE TO HEAD OFF THE ROAD AND ONTO THE GRASS AND CRASH INTO THE GUIDE RAIL. IMMEDIATELY FOLLOWING THE ACCIDENT, I NOTICED THE ABS+VSC+EMERGENCY BRAKE LIGHTS WERE LIT. I HAD THE CAR TOWED TO THE COLLISION SHOP FOR INSPECTION AND REPAIRS WHICH WILL HOPEFULLY START NEXT WEEK. I ASKED THAT THE COMPUTER CODE READOUTS BE NOTED BY THE INSPECTOR WHEN HE ARRIVES. I'VE BEEN DRIVING THIS ROUTE TO WORK FOR 55,000 MILES AND NEVER EXPERIENCED THIS TYPE OF RESPONSE DURING BRAKING. THE VEHICLE HAS A CURRENT INSPECTION STICKER ON IT. *TR