I meant that you should use the Poser menu "Scripts" > "Wardrobe Wizard Menu" but you can start it that way if you want, the Poser menu method will just be less clicks. However if you get that error when you try and run the script Python Shell.py it would appear to indicate that Poser is not finding the core Python modules.

Have you rebooted since installing Poser 8?

What do you get if you try and run Python Shell.py after a reboot?