Unless someone else has a better approach, I'd say that you may be having UAC interference with Vista.  I see by your post that Poser 7 is located within your Program Files folder, an installation that many would attest causes problems with any version of Poser.  In this case, I believe Windows is interfering with the python script and blocking any changes to occur within the Program Files folder.  The only recommendation to remedy this problem, relocate or reinstall P7 into it's own folder outside the Vista's PF folder.  That should solve the script problem.  Parmatic script works very well with this character; I had no problems under XP and PoserPro 2010 to install.