TV momentarily blanks out, shows I put, and display comes back

help, anyone have any idea what might be causing this to happen? I have cable TV via tivo (new unit) no problems, PS3 no problems, Google chrome dongle no problems. While watching tv the screen blacks out a few seconds. Then comes back showing the input that it's using. I also have a Sony sound ar with bass box. If I don't turn down the TV sound, even after choosing surround sound instead of speakers. The TV changes to TV speakers. It's connected by digital cable