I wonder if this isn't a Poser.ini corruption.  By deleting the Poser.ini and letting the application rebuild it might solve your problem.  However, by deleting the file you will need to reestablish you external runtimes.  I am not currently at my own computer to assist you further on how to locate and delete the file (personally, I would change the extension only rather then delete the file), maybe someone else can chime in with the procedures.