title: Cannot find MS.Internal.Media namespace in assembly
body: <p>I've been working on a WPF application. Since I design the UI in Expression Blend 4 and work on the code-behind part in Visual Studio 2010, I constantly switch from one tool to another.</p>
  
  <p>I added some Image controls to an existing Grid and assigned some images to them. In Blend, I built the project and ran it. Worked just fine. When I switched to Visual Studio, I am getting this error:</p>
  
  <blockquote>
    <p>Undefined CLR namespace. The
    'clr-namespace' URI refers to a
    namespace 'MS.Internal.Media' that is
    not included in the
    assembly. C:\Users\Dennis\Documents\Visual
    Studio
    2010\Projects\solutionName\projectName\MainWindow.xaml</p>
  </blockquote>
  
  <p>The designer cannot be loaded with this error pending. However, the project is working in Blend and I can see it just fine there.</p>
  
  <p>The declarations are the following (in the Window):</p>
  
  <pre><code>&lt;Window
          xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
          xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
          xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:MS_Internal_Media="clr-namespace:MS.Internal.Media;assembly=PresentationCore" mc:Ignorable="d" x:Class="projectName.MainWindow"
          Height="272" Width="359" Loaded="Window_Loaded" WindowStyle="ThreeDBorderWindow" ResizeMode="NoResize" Icon="/projectName;component/Images/main.ico"
          Title="Sample Project"&gt;
  </code></pre>
  
  <p>What could be causing this error?</p>