I have had a Dish 622 for a little over a year now. Some of the first HD recordings I made were concerts off of the RAVE channel. I had not watched the oldest ones for a long time. I watched them tonight and there were short intermittent audio dropouts during the concerts yet I could see no corresponding video disturbances. These recordings were perfectly fine before. How can a digital file degrade over time? It doesn't make any sense.

More current recordings do not do this.

Any thoughts?