This is the P5 memory leak. Every frame you render loses system memory, until there is no more fre resources. You may get a request for more swap space, some people claim they can end the render while others claim they can't. I had this problem while working on a 240 frame AVI. Stills weren't an option as I didn't have the space for them. Basically, I found that the leaks are predictable and I could get about 90 frames into the AVI (less with other apps running) before it froze. My solution was just to render 80 frames and then restart my system and render the next set. I used VirtualDub (free) to append the files and what seemed like an insurmountable bug simply became an inexcusable one ;) Also, you will likely find you that you are able to render more frames without shadows than with. I don't know if Poser fails to return all of the memory it consumes, or if there are multiple leaks, but I am able to render much farther into an animation before it stops if i do not use raytraced shadows. I have not had these problems with the P4 renderer...