When Poser uses a model which has an associated OBJ mesh for the first time, it creates a matching RSR in the Geometries folder with the same name. From then on, it loads the RSR whenever that model is used - it loads faster that way. But if Poser goes wrong while it has the RSR open, it can get corrupted. The solution then is to delete only the RSR that's named the same as the OBJ you've created, and Poser will remake it next time you open that figure. If you want to stop it happening again, you can change the RSR's properties to read only once it's been re-made. Exit Poser before doing this, though.