CompuServe Messages

I'm having a problem with shadows disappearing intermittantly from fields (but oddly never whole frames). The scene is this: A helmet sits on a rusted steel plate floor lit solely by one overhead spotlight. The falloff is fairly quick, forming a clear circle on the floor. A humanoid walks in from the darkness, into the spotlight and picks up the helmet. Aside from the humanoid everything, including light and camera, is static. The problem occurs before the humanoid is within the hotspot range, up to the edge — the first 35 frames of the animation. The shadow disappears from underneath the helmet, partially in some fields and completely in others. This occurs on 5 to 7 frames (depending on the spot parameters). However, there are never any two consectutive fields that do not have at least have partial shadow. The effect is a nasty flicker. I have tried using the default settings for the spot, I have tried changing the map size to 750 and sample to 4, I have tried changing the pixel size (1.0 – 1.1), I have tried moving the helmet itself; none of these made any difference except to change when the dropouts occured. The image size is 752×480. The problem is fully reproducible. The only thing that directly effects the problem is moving the Humanoid. Am I missing something? Help! Thanks, John