My TV is a Hitachi model is 55pd8800ta.
I don't think it is a multi screen as the box looks like a text box.
I will have a look tonight when I get home and let you know.
I don't think it is the TV that has caused the black box. I think it is the Harddrive.
It was a button on the harddrive remote that I pushed that made the box come on the screen.
Optional Information: Make: lgModel: dv8743p