我最近从VS2010切换到VS2012。每次重新安装SDK后，设计器都会崩溃。
抛出以下异常：
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
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.Platform.PlatformService.PlatformEntry.get_PlatformCreator()
at Microsoft.Expression.Platform.PlatformService.GetPlatformCreator(String frameworkSpec)
at Microsoft.Expression.Platform.PlatformService.IsCompatibleFramework(FrameworkName hostFramework, FrameworkName guestFramework)
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()
如何修复此错误？请注意，它在VS中的混合和崩溃中工作正常。