title: System.NullReferenceException Object reference not set to an instance of an object
body: <p>So, I get this</p>
  
  <pre><code>System.NullReferenceException
  Object reference not set to an instance of an object.
     at Microsoft.Windows.Design.Platform.SilverlightMetadataContext.SilverlightXamlExtensionImplementations.&lt;GetXmlNamespaceCompatibilityMappings&gt;d__8.MoveNext()
     at MS.Internal.Design.Metadata.ReflectionProjectNode.BuildSubsumption()
     at MS.Internal.Design.Metadata.ReflectionProjectNode.SubsumingNamespace(Identifier identifier)
     at MS.Internal.Design.Markup.XmlElement.BuildScope(PrefixScope parentScope, IParseContext context)
     at MS.Internal.Design.Markup.XmlElement.ConvertToXaml(XamlElement parent, PrefixScope parentScope, IParseContext context, IMarkupSourceProvider provider)
     at MS.Internal.Design.DocumentModel.DocumentTrees.Markup.XamlSourceDocument.FullParse(Boolean convertToXamlWithErrors)
     at MS.Internal.Design.DocumentModel.DocumentTrees.Markup.XamlSourceDocument.get_RootItem()
     at Microsoft.Windows.Design.DocumentModel.Trees.ModifiableDocumentTree.get_ModifiableRootItem()
     at Microsoft.Windows.Design.DocumentModel.MarkupDocumentManagerBase.get_LoadState()
     at MS.Internal.Host.PersistenceSubsystem.Load()
     at MS.Internal.Host.Designer.Load()
     at MS.Internal.Designer.VSDesigner.Load()
     at MS.Internal.Designer.VSIsolatedDesigner.VSIsolatedView.Load()
     at MS.Internal.Designer.VSIsolatedDesigner.VSIsolatedDesignerFactory.Load(IsolatedView view)
     at MS.Internal.Host.Isolation.IsolatedDesigner.BootstrapProxy.LoadDesigner(IsolatedDesignerFactory factory, IsolatedView view)
     at MS.Internal.Host.Isolation.IsolatedDesigner.BootstrapProxy.LoadDesigner(IsolatedDesignerFactory factory, IsolatedView view)
     at MS.Internal.Host.Isolation.IsolatedDesigner.Load()
     at MS.Internal.Designer.DesignerPane.LoadDesignerView()
  </code></pre>
  
  <p>error when I create a new silverlight project.
  File > New > Prooject > Visual C# > Silverlight > Silverlight Application.</p>
  
  <ul>
  <li><p>"Host the silverlight application in a new Web Site" is disabled</p></li>
  <li><p>Silverlight version: 4</p></li>
  </ul>
  
  <p>I don't have this problem on my laptop which has the complete same installation as my home pc.</p>
  
  <p>What is wrong? How can I fix this?</p>
  
  <p>ps.. this error shows up in ANY silverlight project I open.  Whether it's a new one of the one's i've already been working on.</p>
  
  <p><strong>[Update]</strong></p>
  
  <p>But IF I have silverlight 5 installed, wouldn't I be able to choose this when I start a new project?  I can still only choose Silverlight 3 and Silverlight 4. </p>
  
  <p>Also, as stated in the link you gave, I have no siverlight 5 in my "Programs and Featues". </p>
  
  <p>However, a search on google on how to check silverlight version.. I got send to the register to check out a Version Key of silverlight.</p>
  
  <p>The key says my version is: 5.1.10411.0</p>
  
  <p>If there's no silverlight 5 in my Programs and Features, how I can remove silverlight 5?</p>