I had the same problem this morning. I followed your advice, Martin, and all seems to be well. Just waiting to confirm it is recording. I am not worried about losing recorded programmes as I don't keep them for long. I know it might seem odd, but I record interesting things one evening and watch them the next evening while simultaneously recording stuff for the next day. It means that I can discard anything I'm not really interested in and go straight onto another recording. Anyway, thank you for the advice you gave to Cruise.
PS We have had quite a lot of thunderstorms in the north east recently. I wonder if that could have caused the problem?