I have had this Onkyo TX-DS777 receiver for a few years now, and it's always run pretty rock solid. However, whenever I use the optical digital in ports, I experience the same problem: After about a days worth of use, the next day, I fire up the reciever and I don't get any sound from the source. If I unplug the cable at the Onkyo and then plug it back in, I get sound and it works for the rest of the evening. Then the same thing happens again the next day. I've swapped out a few different cables, and I still get the same thing. Any ideas on what this might be? The different sources have included a Sony CD player, a Sony DVD player, a JVC DVD player, and a Toshiba DVD player. It's happened for as long as I've owned the unit which was purchased new. Thanks.