Thanks for your suggestions, Rolfw.
I've already tried that, but to no avail. Allow me to elaborate. When this symtom manifests itself, I switch the digibox back on, where upon it returns the "searching for listings" message and that could go on for hours. Channel 998(Sky welcome) only appears once I change the default LNB transponder value a couple of times (11778,11720,11817,11895,12051 etc). What's confusing is that when it was working 100% the system signal test would show me the following results: signal strength: about 25%; sinal quality:0%; Lock indicator: OK; Network ID and Transport Stream: 0000. (Sorry about the long message). Thanks