Failed to map the path '/' Visual Studio 2013 IDE (Even as administrator)

I use to be able to connect to my Test Server source code via a Network Drive.

I have mapped it to letter K.

My computer (since last restart) won't run the IDE properly, and always displays the error ASP.NET runtime error: Failed to map the path '/'.

 at the top of the aspx file.

I have tried the following:

• Starting Visual Studio as administrator
• Ensuring that my user has FULL rights to the source code folder (both from the network drive and the server)
• Given Network Service and Network users on the server full control over the test server source code folder.
• Changing the AppPool identity on the test server to use my username (as I am administrator on the server as well).
• Creating a new website project and mapping it on another network drive (Still doesn't resolve the problem).

When I access the test server via my web browser I receive no errors. So I know there is no errors in my code.

If I open the IDE on the server using remote desktop then it works with no errors.

I can live with the error on the top of the page, however when I try to access a DataSet or a Control on the page then it doesn't register the control or function as an existing function.

I am now at a complete loss as to how I am going to fix this.

Any ideas on what could cause this issue and how I could fix it?