I just picked up an older Sony STR-AV570 receiver and it's exhibiting some rather odd behavior. I'll turn it on and get a flashing red 'P' and none of the buttons will work, even though I'm not inputting a signal. Turning it off and on a few times will sometimes pull it out of protection mode, and it will work fine for eight hours straight. I turn it off, go to bed, and when I wake up the next morning, it's making this clicking noise near the amps that sounds like a breaker trying to reset itself. If I turn the receiver on at that point, it's already in protection mode. Any idea what's causing this behavior? Is it something I can fix myself? Anything I can do, short of buying a new receiver? Thanks in advance.