McIntosh MC 8207 Power Guard problem.

I’ve posted this elsewhere without results, so posting here and hope I’m not doing it in the wrong place..

My pre/pro is a MX121, set up as a 5.1 system, and the amp is an MC 8207 which has 7 channels. It’s set up according to the manual directions and the two extra channels are currently unused. 

Two nights ago, the Power Guard lights came on for the two unused channels. Seeing as these lights are supposedly active when the amp is overdriven and there’s clipping, I can’t figure out what’s wrong. How could these two channels be overdriven to clipping? When I turn the system on, the center channel Power Guard light also comes on for a bit, then turns off, but the other two stay lit up. I had hoped that it would correct itself after being turned off for the night, but it hasn’t. None of these lights have ever come on before. Anyone else have a problem like this? It seems to be working OK, but somethings wrong, and I don’t want to screw it up. Any suggestions?