Directory Security -Help!

I am trying to setup access privileges for the "Admin" folders on my intranet. Each department in the Intranet has an admin folder that allow the heads of each department to update the news and so on. I want the administrator's logins to be based on their current NT logins on our domain. I changed the Security permissions on the admin folder for each department. I removed "Everyone" and added "Administrator" When the directory is accessed via the web browser, the password challenge works perfect. EX: http://intranet/engineering/admin/ Will bring up the admin page after authenticating the user. HOWEVER: http://intranet/engineering/admin/index.php Will bring up: Warning: Failed opening 'D:\wwwroot\home\admin\index.php' for inclusion (include_path='') in Unknown on line 0 If I change the Security permissions of index.php to include "Everyone", the admin page will display correctly...but it will not be password protected. Is this being caused by the IIS / PHP service being logged in as "localhost"? Is there a workaround for this problem? Any help will be greatly appreciated. If you wish to contact me directly, send an email to paul.wieland@us.atlascopco.com. Thanks in advance. -Paul Wieland