Receiver shuts off abruptly when loud sounds are...

Question

My receiver abruptly shuts off when loud sounds are heard. For example; explosions or loud action scenes. When I turn it back on it says "Check SP Wires". I've checked every wire and they are not touching nor are they reversed. I've had the receiver for about 5 years and never had a problem before. I first thought the input selected had a problem but it occurs on any input selected.