Try this. in File Explorer type this in the address:

%appdata%\Poser Pro\11

In the Poser Pro 11 folder delete these two files (or move them to a safe place while testing to see if this works):

Poser UI Prefs (the numbers will vary depending on the screen resolution)

Poser.ini

FYI the file LibraryPrefs.xml is where the linked runtime are stored. If you need to reinstall saving that file can save you needing to re-link a bunch of runtimes.