I HAVE HAD THE SAME PROBLEM TWICE SINCE I HAVE OWNED THIS VEHICLE. I REPORTED THE FIRST INCIDENT ABOUT 3 YEARS AGO. I NEVER RECEIVED A REPLY FROM YOU OR GM. ON APRIL 30 08 I HAD THE SAME PROBLEM AGAIN. I WAS ABOUT TO PULL INTO THE CARPORT AND WHEN I PUT MY TRUCK IN DRIVE IT SUDDENLY SHOT FORWARD INTO A TRAVEL TRAILER AND DRIVING IT INTO THE WALL. BOTH THE TRAILER AND THE CARPORT WERE DAMAGED THERE WAS NO VISIBLE DAMAGE TO THE TRUCK. *TR