Well, "lock" is probably the wrong term. What I mean is, a program loads a file, and then "watches" the file. If another application changes the file, the program can then reload it to keep it in sync. Textpad (text editor) and Dreamweaver/HomeSite (WebDev/html) do that as well. HOW they do it I don't know exactly, on the Amiga there were system notification flags that would tell programs that this or that status had changed, I assume this is a common feature in a multi-tasking environment. But that doesn't mean texture files aren't cached either. In fact that might explain why some renders crash, as Poser attempts to load in all the textures for the render. This is probably something that Curious Labs would have to answer. Regards- Lemurtek