Thanks. I tried most or all of the things you suggested a couple of years ago when I had the initial ground loop problem, but I may have swapped the cable box since then, so I will try again tomorrow. Six hours of fighting with this is enough for today. BTW, part of the original problem was a torch lamp I had on a separate circuit in another part of the house. Once I removed the lamp, that part of the problem went away.

Also - I made an editing error in my initial post. The TV will recognize the OSD, but not the picture, if the signal is coming from the 975. Everything works perfectly if the signal is coming directly from the Blu-ray. Since my initial post I have also found that every once in a while it will work fine - there seems to be no rhyme or reason as to when it decides to work (I've tried multiple inputs also). I will look to see whether I can adjust for a 1080p signal, but I'm not sure why it would work straight from the Blu-ray and not from the 975.

It is just very frustrating to me that this equipment is so sensitive to a variety of things.