Ah, so the overlay just comes on screen randomly and also tics the volume up a notch. Interesting. It only takes a half hour of use before this happens? And it happens each time?
I'd suspect the avr's circuitry/software before the possibility of such random IR commands from the remote myself but who knows. I'd also try a soft reset of the avr (unplug it for a while) and see if the behavior goes away as a first step myself (and maybe consider a full reset)....but testing the remote by removing the batteries should work fine in that regard.
Reminds me of when my brother and I figured out our neighbor's tv was susceptible to a remote we had, their window was just a driveway's width away, and we'd sometimes freak them out
. I notice an indicator light on my avr lights up when I use my disc player's remote....it doesn't do anything but makes me wonder what possible other IR command from elsewhere could do. I remember a neighbor of mine a few doors away would open both our garages, too
(a radio remote, but....)