Does seem a little odd for that series of Yamaha to have amp section cutting out, just the one set of speakers, the mains I presume?

Also wondering do you use any video upscaling in the avr when it is cutting out? I doubt you are as not many do, but those video chips have been known to create lots of heat when in use which will cause shutdowns.
_________________________
Jason
-----------------
TTTHHHPPPPPTTTT!

My HT