Thanks for including the photo. It makes it very clear what you are seeing.
I'm guessing this occurs when returning from an ad that is sent at a different resolution than the main program but it fails to reset when the ad ends.
Since the control display seems to be normal size, I'm not too hopeful this will help, but ..
Try going to Settings > Display type and setting it to your TV's actual resolution, rather than "Auto detect".
When you change the Display type to a new setting it runs you through several screens:
- A screen where you can choose from the available options on that device.
- A screen where it analyzes your choice to be sure your tv supports it, then gives the option of trying that choice if you wish.
- A screen with a countdown timer and two choices:
Yes, screen looks good
No, I will choose a different setting
The "No" option is highlighted by default. To keep the screen resolution you're currently trying, you need to arrow up to the "Yes" option and click on it before the timer runs out.