Test Movie centers clip off-stage!?

Hi y’all, I’ve been fighting this one for weeks - I’ve tried changing the Document Properties, Publish Settings, and even placing huge white boxes behind the clips I want to preview … all to no avail! What gives?

Basically, whenever I’m inside a nested movie clip, and Test Scene (Control-Alt-Enter), the animation is centered in the upper left of the stage, so I can only see the bottom-right quarter of the animation - the rest is off-stage and not visible! Very frustrating!

I’ve searched Adobe.com, google, and several forums, and found no mention of this issue! Is it a CS4 bug, or am I just doing something really stupid?