Visual Studio xaml设计器未加载

在Visual Studio 2012中无法加载XAML代码的设计器。将显示以下错误。如有任何帮助，不胜感激。

系统。安全句柄已被关闭Microsoft.Expression.HostUtility.Platform.AppContainerProcessDomainFactory.CreateDesignerProcess(字符串applicationPath, String clientPort, Uri hostUri，字典environmentVariables Int32&processId Object&processData)Microsoft.Expression.DesignHost.Isolation.Primitives.ProcessDomainFactory.ProcessIsolationDomain . .男星(ProcessDomainFactoryfactory、IIsolationBoundary、AppDomainSetup、appDomainInfo、FrameworkName targetFramework，字符串标识符，字符串baseDirectory)Microsoft.Expression.DesignHost.Isolation.Primitives.ProcessDomainFactory.CreateIsolationDomain (IIsolationBoundary边界)Microsoft.Expression.HostUtility.Platform.AppContainerProcessDomainFactory.CreateIsolationDomain (IIsolationBoundary边界)Microsoft.Expression.DesignHost.Isolation.Primitives.IsolationBoundary.Initialize ()在Microsoft.Expression.DesignHost.Isolation.Primitives.IsolationBoundary.CreateInstance [T](类型类型)Microsoft.Expression.DesignHost.Isolation.IsolatedExportProvider.Initialize ()在Microsoft.VisualStudio.ExpressionHost.Services.VSIsolationService.CreateExportProvider (IIsolationTargetisolationTarget、ICatalogFactory、catalogFactory、IExportFilter过滤器)在Microsoft.Expression.DesignHost.Isolation.IsolationService.CreateLease (IIsolationTargetisolationTarget)Microsoft.Expression.DesignHost.IsolatedDesignerService.CreateLease (IIsolationTargetisolationTarget, CancellationToken, cancelToken, designerserviceentry条目)Microsoft.Expression.DesignHost.IsolatedDesignerService.IsolatedDesignerView.CreateDesignerViewInfo (CancellationTokencancelToken)(CultureInfo Microsoft.Expression.DesignHost.Isolation.IsolatedTaskScheduler.InvokeWithCulture [T]文化，Func 2 func, CancellationToken cancelToken) at Microsoft.Expression.DesignHost.Isolation.IsolatedTaskScheduler.<>c__DisplayClassa . b_6 ()1.InnerInvoke(System.Threading.Tasks.Task.Execute ()