Thanks for the response, Laser/Mango.
I think I've determined that these systems are just crazy. I tried inserting a DVD and it got to the menu, no problem. Then I put in a HD DVD and it found it and started playing, no problem. Then I tried "Reign of Fire". No go.
So then I cleared both BD and HD memories. Still no go.
Then I tried another BR--"Wall-E," this time. It recognized it and started playing. Then I tried "Ice Age 3," no problem there either.