Are you pretty certain that you’re settings are correct within IIS7, but it’s still not playing ball?

Then try rebooting your server.

Yes I know this is a very drastic measure – but this was the only thing that worked for me.

Things you could check before is the Up Time of the server, in my case I’m using ‘Windows Server 2008 R2’ view this in your ‘Windows Task Manager’ under the ‘Performance’ tab.
My server was denying me access to a SQL server with the following error; which I knew existed and worked when using a local version:

[SqlException (0x80131904): A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 50 - Local Database Runtime error occurred. Cannot create an automatic instance. See the Windows Application event log for error details.
)]


I’m sure that having my server running for over a 150 days had caused it to get itself in to a tizz, with updates that had been installed but not running etc.