[Vilya]

Sounds like a settings conflict between TV and player.

My TV is set to display 16:9 Auto meaning it will display any incoming signal in the aspect ratio received. My disc player "TV aspect ratio" setting is also set to 16:9 auto meaning that it will send whatever aspect ratio the content on the disc is encoded in. All of that works fine unless you are playing an ancient non-anamorphic DVD.

From player manual:

"16:9 Wide/Auto(default)–16:9 content will be displayed in its native aspect ratio, and 4:3 content will be displayed with black borders on both sides in order to maintain the original 4:3 aspect ratio."

Most disc packaging states what aspect ratio the content is presented in and sometimes even gives you a choice. Those early flipper dvd discs had a widescreen image on one side of the dvd disc and a full screen image (4:3) on the other.