My friend has a Sony 500 watt receiver, its about three years old. Just recently, it has been going into "protect" mode during loud action scenes, and sometimes, he gets a drop in sound and then it shortly goes back to normal, but this might occur every five minutes or so. Is this cause of concern, what can we do to fix it, should we rush out and buy a new speaker, what can we do? I should add that his left rear speaker is not as loud as the others, could this be the cause? The speakers are at the same volume, but this one seems less than the others. Thanks for helping us out, we appreciate it.