P5 is liberal about some library organization. The geometry paths are relative, so you can have them either in P5 Runtime geometries or in the satellite Runtime geometries. If you keep the geometries in the main, the library files may be anywhere. The issue with readScript shows that P5 checks the main Runtime first, so it may be faster the keep all geometries there. Your problem may be with textures. They may either be relative, or absolute. You may have moved at texture to a satellite that has an absolute path, or, not moved one that has a relative path. The quick and dirty way to check this - open the library files in a text editor and follow the paths - especially the texture paths. See if things are where you have told Poser they are. Break down your scene. Render one item at a time and find the miscreant. Since texture paths tend to be saved by Poser as absolute - from the HD root - it is possible to have zero textures in any Runtime. Keep them all in the same separate folder - with lots of subfolders, to be sure. Even P4 and P5 together, will play nice with this setup. The main drawback I see- the horrendously long paths if you hand type MATposes or library files when organizing.