If you're using Poser 5, then is it another possibility that you may have re-named or re-located any of your P5 runtime libraries? If so, you might try deleting (or temporarily re-naming to be safe) LibraryPrefs.xml in the prefs folder. P5 will create another one. From my own experience with P5, I can tell you that I use about 20 different runtimes, and sometimes if I (foolishly) re-locate or re-name a few on my hard drive (outside of Poser, and without deleting the libraries from P5 first) then I get a similar problem to the one you describe (XP actually chips in to tell me there's a problem when loading). The problem is fixable if I delete LibraryPrefs.xml. If deleting the file does help cure the problem, it'll be necessary to add your runtime libraries to Poser 5 again - but at least you'll be up and running.