I had same problem. I don't have a fix but look in menu under help and see how much hard drive space is free. On mine, although I had (alegedly) some 30 hours of recording time FREE , the hard drive reported that there was 0% FREE !!! and would not record any additional programmes. I have now deleted all my recordings and still have only 38% of the drive free, although there is absolutely nothing on it.
M P Booth, December 2008