We have an Asp.Net Web Application that we install on client networks for their use. I had one recently where they put the web server on a different domain inside a DMZ, I don't have a huge knowledge of these but I set the Application Pool Identity to Network Service and set the Network Service user to have full permissions on the folders that host the virtual directories. This however doesn't work as I cannot access anything in the virtual directory and I even tried creating a new user on both domains with the same username/password and giving this user access to the folders but still didn't cure it. Also tried the 'Connect As' with a domain\username type username for the domain it was connecting to but still no luck.
The strange thing is I can access the folders themselves within Windows Explorer so I know they can be accessed from this server. They had to set individual ports for things like Sql Server (also on another domain) to give access, is there possibly a port used for Virtual Directories I just need them to open?