Star Trek: The Next Generation - Phase Shift?
In one episode, Geordi and Ensign Ro are 'phase-shifted' so that they cannot interact with physical objects or be seen/heard by the crew. Much screen time is devoted to showing that they fall through chairs and their hands pass right through computer consoles when they try to use them. They walk through walls, and at one point Geordi throws a similarly phase-shifted Romulan spy through the outer hull of the Enterprise and into space.
So...how come they don't fall through the floors during the episode?
The appropriate ST:TNG episode (whose title escapes me...)
on 06-09-2000 and