NBC Experiment in Television - Season 3 Episode 3 The Cube

A man awakens inside a white cube, covered in a four-by-four grid. He has no memory of how he got there and there seems no way out. But as time passes, panels open temporarily to admit an intruder or onlooker. They pop back through their panels but bar the man from going through, pointing out "this is MY door; you'll have to find YOUR door."