This thread will help explain the problem, but unfortunately doesn't solve it. IIS has a problem in that the server authentication method that phpdig uses is not supported under IIS.
What is needed, I think, is an authentication method which compares a user supplied username and password to a database username and password to authenticate. At least for an IIS server, although it would work for Linux/Apache servers, too.
I have a work around myself. Not the best solution, but it works. I change this line in config.php:
PHP Code:
define('PHPDIG_ADM_AUTH','1');
to:
PHP Code:
define('PHPDIG_ADM_AUTH','0');
which turns off server authentication so I can get to the admin panel. When I'm done, I switch that statement back to what it was originally. That's the only way I've found so far that still allows you into the admin panel and still protects you from unauthorized access to it.