i'm new to poser too. i have the same problem, rendering with firefly just gives me a blank avi. (although i made the background green not grey as i am trying some green screen stuff) but i don't know if i really like the answer of make them png's and assemble thenm in another program...although it's a great way to increase the resolution, although most of my stuff is 720X480 video junk. I can get it to render using poser 4 settings, i get a good movie. i wish i could select firefly and get a good avi file. although i will try what has been suggested. any other ideas? is everyone else rendering a avi with firefly and not having this problem? is it just the two of us? hmmm