You can do a full reinstall off the CD. Poser will only over write files with the same names. All your custom characters, props, geometeries etc will not be affected provided that they do not have names that are on the CD. Just to avoid accidents rename your existing Poser folder to "Old Poser" before the reinstall. I have reinstalled off the CD without any trouble. As a tip once you have done this copy the Poser.exe and Poser.rsr files to somewhere safe. Next crash you most likely only need to reinstall these two files.