First, I want to say a huge THANK YOU, THANK YOU, THANK YOU to everyone who responded to my plea for help.

And I would like to especially thank Bob G and GreyFalcon for their suggestion about using a new HDMI cable, a suggestion which I immediately dismissed because it was too simple, and besides, the cable I was using had worked perfectly with the previous computer.

This morning, after spending many hours investigating complex solutions, I decided, what the heck, I have some brand new HDMI cables lying around, so why not try one of them. It worked!

Once again, I was reminded of Occam’s Razor: “the stated principle that, all things being equal, the simplest explanation is usually the correct one.”

Another old saying that I need to remember: “When you hear hoofbeats, think horses, not zebras.”