Installing VS2012 (which includes MVC4) breaks existing ASP.NET MVC 3 app

After installing VS2012 and hereby MVC 4, I have an MVC3 application which now fails with the following runtime error:

Method not found: 'System.Collections.Generic.Dictionary`2 System.Web.Razor.Parser.CSharpCodeParser.get_RazorKeywords()'.

If I create a new ASP.NET MVC 3 project in VS2010 it works ok with razors views. Has anybody else experienced similar issues?