未加载Windows Phone SDK 8.0 XAML设计器

在进行负面报告之前，首先要弄清楚这个问题与其他设计器加载问题有何不同。看看他们和我的例外情况。

设计师工作得很好，我不知道突然发生了什么

注意：我已尝试卸载并重新安装。我已经完成了所有VS12更新。仍然面临设计师的问题

System.NullReferenceException
Object reference not set to an instance of an object.
   at Microsoft.Expression.DesignModel.Metadata.PlatformMetadataBase.GetPlatformAssemblies()
   at Microsoft.Expression.SilverlightPlatform.SilverlightPlatformMetadata..ctor(IPlatformRuntimeAssemblyResolver platformRuntimeAssemblyResolver, IPlatformReferenceAssemblyResolver platformReferenceAssemblyResolver)
   at Microsoft.Expression.SilverlightPlatform.SilverlightPlatform..ctor(IPlatformRuntimeAssemblyResolver platformRuntimeAssemblyResolver, IPlatformReferenceAssemblyResolver platformReferenceAssemblyResolver)
   at Microsoft.Expression.WindowsPhonePlatform.MobilePlatform..ctor(IPlatformRuntimeAssemblyResolver platformRuntimeAssemblyResolver, IPlatformReferenceAssemblyResolver platformReferenceAssemblyResolver)
   at Microsoft.Expression.WindowsPhonePlatform.WindowsPhonePlatformCreator.CreatePlatformInternal(IPlatformReferenceAssemblyResolver referenceAssemblyResolver)
   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.<Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner>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.<Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner>b__e()
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.<>c__DisplayClass16`1.<MarshalIn>b__15()
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()

System.NullReferenceException
Object reference not set to an instance of an object.

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

System.NullReferenceException
Object reference not set to an instance of an object.
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOutSynchronous(Action action, Int32 targetApartmentId, WaitHandle aborted, WaitHandle timeoutSignal)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOut(Action action, Int32 targetApartmentId, WaitHandle aborted, CallSynchronizationMode syncMode, WaitHandle timeoutSignal)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalOut[TValue](RemoteHandle`1 targetObject, Action action, CallSynchronizationMode syncMode)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalOut[TResult,TValue](RemoteHandle`1 targetObject, Func`2 func, CallSynchronizationMode syncMode)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.CreateDesignerImpl(IHostSourceItem item, IHostTextEditor editor, RemoteCancellationToken remoteCancelToken)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.<>c__DisplayClass12.<Microsoft.Expression.DesignHost.IDesignerService.CreateDesigner>b__11(RemoteCancellationToken remoteToken)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.CallWithCancellation[TResult](CancellationToken cancelToken, Func`2 func)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.Microsoft.Expression.DesignHost.IDesignerService.CreateDesigner(IHostSourceItem item, IHostTextEditor editor, CancellationToken cancelToken)
   at Microsoft.Expression.DesignHost.IsolatedDesignerService.IsolatedDesignerView.CreateDesignerViewInfo(CancellationToken cancelToken)

System.NullReferenceException
对象引用未设置为对象的实例。
在Microsoft.Expression.DesignModel.Metadata.PlatformMetadataBase.GetPlatformAssemblies（）中
位于Microsoft.Expression.SilverlightPlatform.SilverlightPlatformMetadata..ctor（IPlatformRuntimeAssemblyResolver平台RuntimeAssemblyResolver，IPlatformReferencesSemblyResolver平台ReferencesSemblyResolver）
位于Microsoft.Expression.SilverlightPlatform.SilverlightPlatform..ctor（IPlatformRuntimeAssemblyResolver平台RuntimeAssemblyResolver，IPlatformReferenceAsemblyResolver平台ReferenceAsemblyResolver）
位于Microsoft.Expression.WindowsPhonePlatform.MobilePlatform..ctor（IPlatformRuntimeAssemblyResolver平台RuntimeAssemblyResolver，IPlatformReferenceAsemblyResolver平台ReferenceAsemblyResolver）
在Microsoft.Expression.WindowsPhonePlatform.WindowsPhonePlatformCreator.CreatePlatformInternal（iPlatformReferenceAsemblyResolver ReferenceAsemblyResolver）中
位于Microsoft.Expression.Platform.PlatformCreatorBase.CreatePlatform（IPlatformReferenceAsemblyResolver ReferenceAsemblyResolver）
在Microsoft.Expression.DesignSurface.Project.ProjectContextBase.Initialize（）中
在Microsoft.Expression.DesignSurface.Project.XamlProjectContext.Initialize（）中
位于Microsoft.Expression.DesignSurface.Project.ProjectContextManager.GetProjectContext（IHostProject项目、IPPlatform、布尔创建）
位于Microsoft.Expression.DesignSurface.Project.ProjectContextManager.GetSourceItemContext（IHostSourceItem sourceItem）
位于Microsoft.Expression.DesignSurface.DesignerService.CreateDesigner（IHostSourceItem项、IHostTextEditor编辑器、CancellationToken cancelToken）
在Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.c\uuu DisplayClass10.c\uu DisplayClass12.b\uf（CancellationToken cancelToken）
位于Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.CallWithCancellation[TResult]（IRemoteCancellationToken remoteToken，Func`2 Func）
在Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.c__DisplayClass10.b__e（）中
在Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.c__DisplayClass16`1.b__15（）
在Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker（）中
System.NullReferenceException
对象引用未设置为对象的实例。
服务器堆栈跟踪：
位于Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion（NestedCallContext NestedCallContext，BlockingCall调用，WaitHandle timeoutSignal）
位于Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalIn（Action Action，Int32 TargetPartmentId）
位于Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn（IRemoteObject targetObject，Action）
位于Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn[TResult]（IRemoteObject targetObject，Func`1 Func）
位于Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner（IRemoteHostSourceItem remoteItem、IRemoteHostTextEditor remoteEditor、IRemoteCancellationToken remoteToken）
在System.Runtime.Remoting.Messaging.StackBuilderSink.\u PrivateProcessMessage（IntPtr md，对象[]参数，对象服务器，对象[]和输出参数）
在System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage（IMessage msg）中
在[0]处重试异常：
at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage（IMessage reqMsg，IMessage retMsg）
at System.Runtime.Remoting.proxy.RealProxy.PrivateInvoke（MessageData&msgData，Int32类型）
位于Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner（IRemoteHostSourceItem remoteItem、IRemoteHostTextEditor remoteEditor、IRemoteCancellationToken cancelToken）
在Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.c__DisplayClass8.b__6（IRemoteDesignerService d）中
在Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.c__DisplayClass4`2.b__3（）中
在Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker（）中
System.NullReferenceException
对象引用未设置为对象的实例。
位于Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion（NestedCallContext NestedCallContext，BlockingCall调用，WaitHandle timeoutSignal）
位于Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOutSynchronous（操作操作，Int32 TargetPartmentId，WaitHandle中止，WaitHandle timeoutSignal）
位于Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOut（操作操作，Int32 TargetPartmentId，WaitHandle中止，CallSynchronizationMode syncMode，WaitHandle timeoutSignal）
在Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.Marshallout[TValue]（RemoteHandle`1 targetObject，Action Action，CallSynchronizationMode SynchMode）
在Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.Marshallout[TResult，TValue]（RemoteHandle`1 targetObject，Func`2 Func，CallSynchronizationMode syncMode）
位于Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.CreateDesignerImpl（IHostSourceItem项目、IHostTextEditor编辑器、RemoteCancelationToken remoteCancelToken）
在Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.c__DisplayClass12.b__11（RemoteCancellationToken remoteToken）
位于Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.CallWithCancel