I'm sorry for the inconvenience, yaminoyugi! It sounds like it's just a Picture size issue There's an option within the picture menu for Picture size you're going to want to make sure that's set to 16X9. If it is set that way and you're still receiving the same issue you would need to contact you cable service provider to walk you through changing the output resolution of the cable box.

Hope this helps!

Regards,
HD Tech