MY VEHICLE IS 2005 CHEVY SILVERADO 1500 PURCHASED IN 2007 WITH MILEAGE OF APPROXIMATELY 47,000 MILES AT THE TIME OF PURCHASE. UPON DRIVING THEVEHICLE FOR THREE MONTHS, MY SPEEDOMETER STARTED STICKING INTERMITTENTLY, BUT WOULD RESET. SINCE, MY SPEEDOMETER STICKS ON A DAILY BASIS, SOMETIMES ALL DAY. THE ONLY REMEDY HAS BEEN TO TURN MY VEHICLE OFF AND BACK ON, WHERE AS MY SPEEDOMETER GOES DOWN AT FIVE MILE PER HOUR INCREMENTS UNTIL BACK AT ZERO. IN THE LAST THREE WEEKS, MY TACHOMETER HAS ALSO MALFUNCTIONED AND DOES NOT READ AT TIMES, THEREFORE MAKING IT IMPOSSIBLE TO KNOW HOW FAST I AM GOING NOR HOW HIGH MY ENGINE IS IDLING OR INCREASING/DECREASING IN SPEED. THERE IS NO APPARENT EVENT LEADING UP TO THE FAILURE AND MY CONCLUSION IS THAT THE INSTRUMENT CLUSTER IS DEFECTIVE IN ITS ENTIRETY. IN MARCH OF THIS YEAR I WAS TRAVELING IN OKLAHOMA DURING A SUDDEN SNOW STORM IN WHICH TRAFFIC WAS TRAVELING AT AN ESTIMATED 20-30 MILES PER HOUR. I ACCELERATED TO AN UNKNOWN SPEED, HOWEVER NOT EXCESSIVELY. I LOST CONTROL AND MY VEHICLE SLIDE ACROSS TWO LANES OF TRAFFIC OPPOSITE THE LANE I WAS IN AND I SLIDE INTO A DITCH IN WHICH MY BOTTOM AIR DAM WAS TORN OFF. I WAS ABLE TO REPAIR THE DAMAGE HOWEVER I ONLY ACCELERATED BECAUSE I THOUGHT I WAS TRAVELING AT TEN MILES PER HOUR. WHEN MY VEHICLE CAME TO A REST IN THE DITCH, MY SPEEDOMETER WAS STILL AT TEN MILES PER HOUR. A STATE TROOPER DID ASSIST ME BY GETTING A TOW TRUCK, HOWEVER NO REPORT WAS FILED BY ME. I BELIEVE THAT IF I HAD KNOW HOW FAST I WAS