Good answers, but if it always happens with the same characters it is probably the .RSR problem that X-perimentalman described. As he said, delete the offending .RSR in the appropriate Geometries folder and let Poser rebuild it from the .OBJ file in the same folder. After you get the problem figure to open again, be sure to let Poser close that scene and exit properly because it only writes the new .RSR to disk as it closes the file. If you crash out, the new .RSR will be corrupt once again the next time you try to use that figure.