Why would loading a XAML file faile on a brand new, unaltered Silverlight project?

Question

Why would loading a XAML file faile on a brand new, unaltered Silverlight project?

This is the first time I have started a silverlight project on the current machine I am on with Visual Studio 2010. Until now, I have been programing ni ASP.NET.

When I first tried to start a new Silverlight project, I was told I needed to install a fresh copy of Silverlight. I had to uninstall Silverlight as well as my versions of the Silverlight SDK. After uninstalling and reinstalling (now I have Microsoft Silverlight 5.1.20513.0 and Silverlight 4 SDK 4.0.50826.0) I was finally able to create a Silverlight Project. But the XAML code instantly failed to load in the IDE

http://i67.photobucket.com/albums/h292/Athono/ASP_DOT_NET%20and%20CSS/outofthegate02_zps0bd33d95.png

<UserControl x:Class="SilverlightApplication4.MainPage"
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"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400">

<Grid x:Name="LayoutRoot" Background="White">

</Grid>

http://i67.photobucket.com/albums/h292/Athono/ASP_DOT_NET%20and%20CSS/outofthegate01_zpse0f20845.png

   System.NullReferenceException

Object reference not set to an instance of an object. at Microsoft.Windows.Design.Platform.SilverlightMetadataContext.SilverlightXamlExtensionImplementations.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()

Any suggestions?