We had a very similar problem with our Grundig Sky Digibox. About a year ago, Channel 5 suddenly 'disappeared' reporting 'no satellite signal being received'. All other channels OK. A couple of months ago, BBC2 became intermittent and eventually also permanently reported 'no satellite signal being received'. Gradually, other channels, ITV3, BBC News 24, were similarly affected - all reporting 'no satellite signal being received' while others, BBC1, ITV1 worked perfectly well. In addition to the Sky box, we also have a Free-to-Air box. When this was connected, in place of the Sky box, everything worked fine (for those channels that were able to be received FTA, e.g. BBC2, News 24. After much 'fiddling about' we sought advice and were told that the 'old' Grundig Digibox had a very weak power supply system (whatever that means!!) and, if we replaced it (the power supply), it should do the trick. Less than totally confident, we sent the box away to a local specialist who replaced the power supply (total cost, including return postage, 80 Euros). The repaired box works perfectly and all channels, including Channel 5, are now available without any problem at all. In our case, at least, 'replacing' the power supply was the complete and instant solution. Depends, I suppose, whether you too have the 'old' Grundig box. Hope this helps anyway.