A rather common issue when installing an ASP.NET MVC powered by .NET Framework 4 on IIS 7.0 or higher is the sudden appearance of a HTTP Error 403 - Forbidden upon launch:
HTTP Error 403.14 - Forbidden - The Web server is configured to not list the contents of this directory.
The text might vary, but the meat is the same: despite anonymous authentication is enabled and all the permissions are set (IUSR, IIS_IUSRS, NetworkService), the web application refuses to run properly.
Well. the first thing to do obviously is to ensure that what we mentioned above is properly set: anonymous authentication must be set to enabled (Authentication icon in IIS settings) and all the aforementioned users permissions must be properly assigned (filesystem wise). If everything has been handled correctly, you can proceed to add the following section to your web application's web.config file:
Once you do that, you can try to deploy your application again: the issue should be solved.