Blue screen. I have a vizio 42 lcd, my problem is in hdmi with the use of sat dish it plays fine

Question

I have a vizio 42 lcd, my problem is in hdmi with the use of sat dish it plays fine for an hour or so then the screen go's blue. I have sound but no picture. If i hook up the rca jacks to the receiver and the back of the tv it works fine all the time. But in both hdmi ports it will work for a while but then go's back to blue screen and again no picture. Any help would be great.