Check the angle of the camera versus where the various lights are. If the camera plane passes through a spot at just the right distance, then all it gets is the light itself, as you have a lightsource between the camera plane and the rest of the image, effectively 'blinding' it. Also check your camera path, and see if it is clipping into the background structure. Many of those props have multiple layers, some translucent, to achieve depth effects. You definitely want to render animations as single frames, as it is so much easier to resume from where Poser choked, for whateve reason. It would also make it easier to debug your light issue, as you could examine each flawed frame. Just about any image editor (from Quicktime and Magix Video Studio at the low end, to Premiere at the high end) will open an image sequence and composit them into your choice of file format. Most of them depend on the codecs you have on your system. Softriver also has a point about the frame rate; 20fps is very non standard, and if a player has a 'default to X if framerate unrecognized' type setup, then it will try and tween the extra frames it needs to be happy. And the results can be bizarre. But check the lighting and camera path first.