Just a shot in the dark here, but I have a 9200 and sometimes in the morning - the SD channel I am viewing is full screen. Pressing (swap) normally clears it up. Again, not sure if this is your issue.
I too have a 9200, it is not in stretch nor is the tv. I will try the swap, I did have to do a hard boot this morning as I had the black screen with sound. thx