Thanks for the ideas.
Our 922 is in an open cabinet, so I *think* the heat is okay, although I will explore that further. And we just upgraded our electrical panel and all our circuit breakers a year ago.
The remote backup of timers is something I will look into some more, thanks.
I just wanted to add that I found a new angle to this problem and I wonder if it'll shed any more light. So, we have just one television. If the setting is on Duo mode, then everything's haywire - the PIP doesn't work, really, half the buttons on the remote don't work as designed. On Solo mode, everything works as it should. Here's the thing, though. I recently discovered that when my husband slings from his iPhone (so, in other words, "tv2" is in use), then stops slinging, we get the weird-partial-black-screen thing the next time I try to use the guide or the menu, etc. Even if I'm watching the main tv and everything was working normally, and I haven't turned it off or reset or anything at all, the very next time I try to go to the guide or something, we get the glitch. Also, a few times after resetting, the 922 has defaulted to Duo mode for some reason. So, I have to go into the menu and switch it to Solo mode. The moment I switch into Solo, there's the glitch again. So, I'm sensing that this issue has something to do with switching between Duo and Solo modes?