sounds like your windows is going a bit funny, strangely mine was upto a little funnyness a week ago, so i formatted the hell out of my hard drive and intalled windows again, now im happy again... Try typing in AVI CODEC into google and see if there are any codecs you can download, as this may help. Don't bother with the MJPEG AVI codec, as i know Poser doesn't use that style of compression, i know this because my poser was making AVI movies before i downloaded the codec, (I needed this codec because my Digital camera uses it.. silly thing)

Getting old and still making "art" without soiling myself, now that's success.