TOSHIBA 36" CN36X81 1999 NO PICTURE

I HAVE A 1999 TOSHIBA CN36X81 CINEMA SERIES HD I WAS WATCHING LAST NIGHT AND THE PICTURE WENT BLACK FROM THE OUT SIDE TO THE CENTER ALL FOUR SIDES ? IT WILL TURN OF & ON GO THROUGH ALL THE CHANNELS EVERY THING WORKS FINE BUT NO PICTURE ANY IDEAS?