I had some similar quirks crop up during a video capture (totally unrealted to Poser). The avi file format is written based on which version of Media Player you have, as MS is always tweaking things (and not always for the better) and can wreck some of the codecs. Most of the programs look for avi in Windows, but poser may load it's own codec. Upgrading media player might be one solution. Of course, I'm one of those barbarian mutants that actually edits in After Effects.