Ok. The set is connected to a Freeview HD hard drive recorder and also to a blu ray player. I will try the retune and maybe the software update if that is relevant. It is not a major problem as it appears only in the top left hand corner of the screen and after several short appearances it seems to go away. I just wanted to make sure it wasn't something that if I didn't ask about it might become a major issue. Does this seem the best option to you?