title: set property 'system.windows.resourcedictionary.deferrablecontent' threw an exception
body: <p>I'm running Visual Studio 2012, when I add a new File/Reference to a project the message box appears showing the error message </p>
  
  <blockquote>
    <p>set property 'system.windows.resourcedictionary.deferrablecontent' threw an exception</p>
  </blockquote>
  
  <p>I read an MSDN article suggesting to run the command <code>devenv /resetuserdata</code> on visual studio command prompt to resolve this problem, tried it but didn't work for me. In fact the command prompt shows the <code>Unknown Error</code> message.</p>