[Doitsu]

Apparently my code doesn't work with your Windows 7 version and the external interpreter. Enabling the Use Bundled Python option might fix this problem, because the Python version bundled with Sigil is newer than your external interpreter.

If enabling the Use Bundled Python option doesn't fix the problem, you'll have to change the plugin source code:

1. In Sigil, select Edit > Preferences > Open Preferences Location.
2. Double-click the plugins folder and then double-click the PrincePDF folder.
3. Open plugin.py with a text editor (e.g. NotePad oder Notepad++) and change the following line:
   
   from:
   
   

       prince_path = os.path.join(os.getenv('programfiles(x86)'), 'Prince', 'engine', 'bin', 'prince.exe')

   to:
   
   

       prince_path = os.path.join('C:\\Program Files', 'Prince', 'engine', 'bin', 'prince.exe')

   (Make sure to only change the text marked in Magenta.)

This should take care of the problem, if it doesn't you could always use Jellby's much more robust and sophisticated Calibre plugin.