Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Disappointed

I am generally satisfied with the operation of the receiver. (I have not tested its HDMI capabilities though.) But it exhibits a problem that I have not read about in any reviews. The problem is that after it is on for a time (say, approximately 30 minutes) at a volume level of 40, or so, it shuts down (and the standby light continually flashes) when the volume is changed by at least 2 increments, increase or decrease. This occurs even without any wires (speakers and other component) connected to it. I have talked to Onkyo technical service a couple of times. Their diagnosis was that its protection circuitry was malfunctioning. They recommended that I take/send it back to the dealer that I bought it from for exchange, or refund.