All PHP Pages Error 401

[jshels]

Hi,
I'm running Plesk on a Virtual Dedicated Server. At first all PHP pages were returning with 404, in Handler Mapping I've configured *.php to c:\plesk\admin\bin\php5isapi.dll and now they're coming back as 401. I assume the permissions on this file are incorrect. If that is the case how do I change them and what should they be?

Thanks