I have an IIS 7 website configured with three web applications, where one of the domain.com/app1 located at C:\inetpub\wwwroot\app1 needs to respond directly from domain.com root.
So, on the Default Web Site, I've selected from the Application Pool the app1 (see image) and pointed to the application path. The problem is it only works if I append Default.aspx to the URL http://domain.com/app1 versus running it from http://domain.com. I even moved up Default.aspx to the top of the default document listing.
And the final problem is the other two applications are failing also included in image.