> Both have aliases defined, both can be browsed to by other machines with a helloworld.aspx type file located in each installation's root file so presumably the installation operates and the aliases are valid.
No. The DNN Alias has no bearing on a Hello World ASPX file accessed directly on the URL, even in the same folder/site. DNN's alias is used solely within DNN, as part of the URL rewriting.
If you set up DNN from the localhost, the installation was done from http://localhost/{DNN_Virtual_Directory} where {DNN_Virtual_Directory}is the name you gave to the virtual directory for DNN, usually DotNetNuke. That means if you type in http://localhost/{DNN_Virtual_Directory} while browsing from the server, you will get to the site correctly.
But "localhost" is only valid on the physical web server. Off the web server, you need to access it with a host name that points to the server's IP address or the IP address itself. That means you would access it as http://{Hostname}/{DNN_Virtual_Directory}/. Only DNN doesn't know where the heck that is, because the DNN installation is for "localhost" so DNN redirects your browser to http://localhost/{DNN_Virtual_Directory}. Only that doesn't work because you are not on the web server.
To fix this, you add an Alias in DNN as posted several times. This alias must match the URL you are requesting for DNN to process it correctly. So if you are accessing your DNN site as http://www.sample.com/DotNetNuke/Default.aspx, the Alias you need to add is www.sample.com/DotNetNuke.
It's definitley not a SQL permissions issue, you'd see an ASP.NET error. If you're seeing a Hello World page it's not an IIS permission error.
If this doesn't fix you, post the exact URL you access the site with from the server, the exact URL you attempt to access it with from off the server and the exact Aliases you have configured in DNN.
Jeff