Help me help my neighbor

[JimShaw]

He has a 5.1 system using Onkyo TX SR605 receiver, Panasonic DMP BD85 player hooked up to Polk RM101 speakers and a Polk sub.

The problem: In the past my neighbor (every once in awhile) would hear a loud pop in his speakers and the surround sound would turn off leaving only the TV speakers able to work. In a short time, the surrounds would turn back on.

A couple days ago, the loud pop was heard again, the surround speakers turned off and now they no longer turn back on.

I was called over and I checked out everything that I could: wire connections, etc., etc. Everything is OK except no surround sound.

My thinking is the Onkyo's circuit breaker has been tripping and now gone bad?????

Is this a possibility or is there something else we might try???