I had Poser 3, but no file, it seems, what has a bum. I have just an idea. If you rename your "old" bum files into "bmp". Then open your people or animal in Poser4 and apply the renamed bmp file as a bump map (will be converted then) and try to save PZ3 this way ??? It may work. I only have the Raptor from Poser 3 Zygote, but it has no bum file?? Guitta