After yesterday\'s Windows Update, I seem to have issues building my projects.
Related Windows Updates could be: ASP.NET MVC 2.0: KB2993939 ASP.NET MVC 3.0:
The recent updates have incremented version numbers
3.0.0.0 -> 3.0.0.1 and 4.0.0.0 -> 4.0.0.1
I had to remove the reference and re-add (System.Web.Mvc is found in Assemblies >Extensions are of the Add Reference dialogue)