I have an Onkyo TX-SR707 that has worked fine for four years. For the past three nights it has not been communicating with any of my speakers when I turn it on no matter what listening mode I set it on. the speaker display on the receiver is blank when this happens. The past two nights it has suddenly recovered the connection w/o my doing anything. So far tonight it has not. Any ideas what this could be or do I need to shoot this receiver?