An HDMI cable or port that is going out could cause this. If the HDMI cable isn't electrically sound any longer because of the connector or actual cable, yeah, it could make some funky stuff happen.
Interesting; I never would have imagined that.
My educated guess is that the HDMI port on your receiver is bad. Given its age and heat output, I'd say you got a lot of good years out of it.
This is what I originally suspected (hence the thread) but wasn't sure; indeed, no complaints about the number of years we got out of it -- and aside from the HDMI out issue, everything else is still working top notch (amplification and processing stages). It really has been one of the best pieces of consumer electronics I have ever owned, and it is what is keeping me in the Onkyo family (I know they had their quality control issues following this generation of AVRs, and, unfortunately, with this new takeover, it seems like their overall build quality is highly suspect...but I'd still be willing to keep one in my system).
You'd never guess this thing pumps out 90 watts per channel (most likely two channels driven, but still...) -- it performs like a MUCH beefier amp, especially given where it landed on the price scale (the 600 series was always an awesome value proposition from Onkyo). A couple of things still irk me, though, and hopefully I can get past this with a new model....I don't think this unit should have been given the small, limp, lifeless, plastic volume knob (the 605 started life at a $600 price point -- not exactly SUPER cheap, so I don't think this thing deserved the plastic controller). It really does perform and punch beyond its price point, and I don't believe the knob is an indicator of the muscular brawn this amp puts out (once you got into the 700 series the knobs turned to aluminum with the blue light ring around them, if I'm not mistaken; but IMO the 605 should have gotten this treatment for an original $600 tag).
Of course, it seems like brand new AVRs, even at the flagship level, are coming with plastic volume controllers, too, so this may not be something I will be able to satisfy...
Additionally, the unit doesn't have the processing power (and I don't fault it for this, I suppose) to take a two-channel DTS-HD Master Audio signal and apply some kind of Pro Logic II processing so it can play through channels beyond the left and right mains. For example -- I own a bunch of Scream Factory Blu-rays that only come with either a 2.0 stereo or 2.0 mono DTS-HD MA track, and played back through my 605 (bitstreamed from my player), these are forced into the left and right channels (in my system, Polk RTi12 towers) in Stereo mode, which causes a weird "comb filtering" effect and makes dialogue sound really weird. Sometimes, if I am sitting PRECISELY and EXACTLY in the sweet spot, I can catch a phantom center effect where the dialogue appears to be coming SOMEWHERE from the screen...but not often. Now, I understand that in these circumstances I can switch the disc player to output PCM and then utilize the 605's processing modes so the tracks don't play just from the center, but I would rather always leave everything set to bitstream.
At any rate, I'm just venting....I don't know if I will conduct any tests to see if the HDMI cable is the issue, but in the meantime, let me ask this: It is probably the HEAT from the HDMI out chip that is causing this failure?