For a couple of weeks now, I have been unable to view or record channel 4HD programs on Satellite without retuning the system. Terrestrial isok but is affected by weather conditions here! All recordings are for no time. And the channel is blank. Once retuned it works fine for a short time (not sure if hours or overnight) then back to blank screen! Any ideas? Or what I can give you to help diagnose the issue? Means I miss the Grand Prix races amongst other things!