I just wanted to add that I too am now intermittently seeing the same optical input problems with at least two optical inputs. At first I thought it was just my DirecTV DVR, the cable it uses, or unusual numbers of errors in the audio stream from the DTV satellite, because I had only ever seen it when using that component. Then, I was playing a video game the other day using a different optical input and cable, and the same exact thing happened: the input lost signal lock and could never regain it despite constantly trying. When this happens, the display constantly switches back and forth between 'Dolby D' and 'S/PDIF Unlock'. It will sometimes recover, but it usually continues to switch once this happens. Temporarily switching to a different digital input, or even the analog input, and back does not clear the problem. It seems to clear after the system is off for some time. I was wondering if anyone had pursued this further and had any suggestions.