Watch the task manager, if Poser.exe's mem usage is updating it is still running. (Dont jump the gun here, Poser may be still for a few moments, but not minutes) Poser is a RAM hog and may want more. Try smooth polys off. Change the render size. Adjust camera angle or focal. Next I would delete characters and props one at a time from the scene. (Start with the high poly stuff to reduce render time). It's going to be something, possibly limits to what poser can do. A screenshot of the render settings might shed some more light.