I was watching a 2 hour movie I tivoed the other day. With about 20 minutes left in the movie, a recording of the home shopping network replaced the movie I was recording. Nothing appeared on the screen indicating the channel had changed, but it did. The same thing happened while I was watching an auto race (my viewing was about 30 minutes behind real time). But with about a third of the race to go, it switched to HSN. Any ideas? Thanks.