I don't know if this is going to help us narrow down some of these render issues ... but the scene that I was having problems with when I posted response #8 had a mixture of ray traced and shadow mapped lights. The problem went away when I used all ray traced lights. So, the problem seems to be with when Firefly renders shadow maps. What I see is that Firefly gets hung up when it is loading objects and materials, and I see no action from the CPU. When I start the task manager there is no CPU activity at all, and it also shows that Poser 5 is still running (in other words, it doesn't say "Not responding". The only way I can get out of it is to end the task. There have also been times that the render stops after a partial render, without any warning. Could these also be memory issues? I have 1 Gig of RAM, a 1.8 GHz CPU, and two 80-gig hard drives.