Getting an Access Denied error 401.2 when trying to run a new ASP.NET Web Application in VS 2012

I’ve got a new ASP.NET web application I’ve made, and copied files over from a ASP.NET web site application into it. I’ve converted the .aspx files into web application (didn’t know that I had to do that until today), and now it all works, with the exception that I’m getting an “Access is denied” error (401.2). I’m using VS 2012, .NET 4.0.30319, ASP.NET version 4.0.30319.18446
 
This is not running under IIS, it’s using the localhost and auto generated port number that VS 2012 does when you run it from within VS 2012.