Instrument Panel problems of the 2006 Chevrolet Silverado

In my 2006 Chevrolet Silverado the speedometer turns off and on and gets stuck. I know for a fact that there are 4 other vehicles in our family that do the same thing. You will just be driving down the road and it either turns completely off or it goes up to 120mph or gets stuck were you were in speed. We have received two tickets because of this I would like to know what can be done about it? it is obviously a default if it is happening in all of our vehicles.