My appols. This will be caused by one of two things: one of the cables has a problem. One of the LNB ports is faulty.
Assuming that you have four port LNB, you need to go through some swapping in logical fashion to find out which one (cable or LNB Port) has the problem.
Having done that there is just chance that it is the box but the other two are more likely.
T, August 2009