did you receive a new card for your sub box in the last few weeks? or have you tried a factory reset and rescan?
as I said read the Nagra 3 thread, your box is coming to its end, most of the UK is now on N3 or in its last stages of being switched, your box wont work, scanning it may bring back one or two chans, but in a matter of a week or two it will be gone, you need the Kryptview A780 or the SV6 box for continued viewing. Do it now while you can get one as they will fly off the shelves, the WC is about to start