Here are some details on my system.
Samsung TV-2 prong
Oppo-2 prong
Marantz-2 prong
Dish box-3 prong
All of the above components were plugged directly into the wall individually.I went ahead and put them all on power strip today.
Powered sub-2 prong.Plugged into the wall directly by itself
Seiki blu ray player-2 prong
Roku box-2 prong
The above two components were both plugged into the wall individually.I put them in a power strip today also.
The only plug I had with a ground was the Dish box.Now I have two since I utilized the power strips.Everything is plugged into the same wall.Should all be on the same circut.Does this shed light on anything.
So basically you have two grounds, the Dish AC plug and the ground from your satellite system
There is possibly a third. Is your Roku Box getting its steam via wireless or Ethernet cable?
Now I would get an outlet tester at Home Depot and make sure the live and neutral is not reversed at your outlet.
Next what happens if you pull every input from the back of the Marantz? Do you get lines going across the screen? TV connected to the Marantz by one HDMI cable and no others. There should also be no cables going to the TV from any other unit other than the Marantz.
If not, then plug each input in to the Marantz individually. Just one unit connected to the Marantz at a time. You should have only the HDMI cable going to the TV, and no other connections to the TV for the test.
See if all, or only some of the peripherals cause the problem.
Please report back with the results.
Unfortunately your only ground is the Dish DVR which has two grounds. This is not an optimal situation.