Here's a little rundown of what's caused poser 5 to lock up for me in the past: Rendering at too high a resolution (800dpi or more). Rendering an image too large (3000 by 3000 dpi). Trying to use smooth polygons on something that has lots of them. Trying to use texture filtering on high resolution maps (not needed anyway :P). Using gaussian of sinc samplnig for shadows when I have lots of lights. Having an image with lots of shading nodes (they eat memory) I would suggest trying a render on the default 'Draft' setting at the size and resoltion you want and then slowly building up the render quality (adding shadows etc) to see when it freezes. If you can't even get a draft render then something in your scene is at fault and deleting stuf is your only real option.