Visual Studio Express 2012 for Windows 8, System.ArgumentNullException

Visual Studio Express 2012 for Windows 8 で ItemsPage.xaml を開くと エラーが発生します

System.ArgumentNullException
Value cannot be null.
パラメーター名: key
at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
at Microsoft.Expression.DesignModel.Metadata.PlatformMetadataBase.NewReplacedExternalType(PlatformMetadataBase platformMetadata, IPlatformTypes sourcePlatformTypes, IAssembly assembly, Type keyType, Type replaceType, ITypeId baseType, ITypeId neutralType, IXmlNamespace xmlNamespace, String clrNamespace, AttributeCollection attributes, ProxyPropertyDescription[] properties)
at Microsoft.Expression.DesignModel.Metadata.PlatformMetadataBase.NewReplacedExternalType(PlatformMetadataBase platformMetadata, IPlatformTypes sourcePlatformTypes, IAssembly assembly, Type keyType, Type replaceType, ITypeId baseType, ITypeId neutralType, IXmlNamespace xmlNamespace, String clrNamespace, ProxyPropertyDescription[] properties)
at Microsoft.Expression.WindowsXamlPlatform.WindowsUIXamlPlatformMetadata.OnInitialize()
at Microsoft.Expression.WindowsXamlPlatform.WindowsUIXamlPlatform.Initialize()
at Microsoft.Expression.Platform.PlatformCreatorBase.CreatePlatform(IPlatformReferenceAssemblyResolver referenceAssemblyResolver)
at Microsoft.Expression.DesignSurface.Project.ProjectContextBase.Initialize()
at Microsoft.Expression.DesignSurface.Project.XamlProjectContext.Initialize()
at Microsoft.Expression.DesignSurface.Project.ProjectContextManager.GetProjectContext(IHostProject project, IPlatform platform, Boolean create)
at Microsoft.Expression.DesignSurface.Project.ProjectContextManager.GetSourceItemContext(IHostSourceItem sourceItem)
at Microsoft.Expression.DesignSurface.DesignerService.CreateDesigner(IHostSourceItem item, IHostTextEditor editor, CancellationToken cancelToken)
at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.c__DisplayClass10.c__DisplayClass12.b__f(CancellationToken cancelToken)
at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.CallWithCancellation[TResult](IRemoteCancellationToken remoteToken, Func`2 func)
at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.c__DisplayClass10.b__e()
at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.c__DisplayClass16`1.b__15()
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()

System.ArgumentNullException
Value cannot be null.
Parameter name: key

Server stack trace:
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal)
at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalIn(Action action, Int32 targetApartmentId)
at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn(IRemoteObject targetObject, Action action)
at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn[TResult](IRemoteObject targetObject, Func`1 func)
at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner(IRemoteHostSourceItem remoteItem, IRemoteHostTextEditor remoteEditor, IRemoteCancellationToken remoteToken)
at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Object[]& outArgs)
at System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(IMessage msg)

Exception rethrown at [0]:
場所 System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
場所 System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner(IRemoteHostSourceItem remoteItem, IRemoteHostTextEditor remoteEditor, IRemoteCancellationToken cancelToken)
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.c__DisplayClass8.b__6(IRemoteDesignerService d)
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.c__DisplayClass4`2.b__3()
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()

System.ArgumentNullException
Value cannot be null.
Parameter name: key
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal)
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOutSynchronous(Action action, Int32 targetApartmentId, WaitHandle aborted, WaitHandle timeoutSignal)
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOut(Action action, Int32 targetApartmentId, WaitHandle aborted, CallSynchronizationMode syncMode, WaitHandle timeoutSignal)
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalOut[TValue](RemoteHandle`1 targetObject, Action action, CallSynchronizationMode syncMode)
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalOut[TResult,TValue](RemoteHandle`1 targetObject, Func`2 func, CallSynchronizationMode syncMode)
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.CreateDesignerImpl(IHostSourceItem item, IHostTextEditor editor, RemoteCancellationToken remoteCancelToken)
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.c__DisplayClass12.b__11(RemoteCancellationToken remoteToken)
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.CallWithCancellation[TResult](CancellationToken cancelToken, Func`2 func)
場所 Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.Microsoft.Expression.DesignHost.IDesignerService.CreateDesigner(IHostSourceItem item, IHostTextEditor editor, CancellationToken cancelToken)
場所 Microsoft.Expression.DesignHost.IsolatedDesignerService.IsolatedDesignerView.CreateDesignerViewInfo(CancellationToken cancelToken)

原因はわかりません。