So since it has been determined that it is a hardware issue check all the outdoor connectors for corrosion. Check the lightning arrestors on the side of the house and there could be a test point up on the roof near the dish.

Do you have more than one receiver. Check to see if this problem is ocurring on other receivers. By doing this you can narrow down the connectors and parts that could be causing you the problem.

Hope this helps,

Dave T