I think we need a little more info to be able to help you out. When exactly do you get the error message? When you load the prop? Or when you move or manipulate it? In other words, what action do you think caused the error? And, oh, which prop exactly is it? A possible solution: delete the .rsr file of the prop (like VirtualSite said). Poser will generate a new one. As soon as Poser created it, make the file 'read-only', so it won't be screwed again (excuse my language) :) Hope it helps