Could not mock System.Windows.Window with Natural Mock?

I've encounterred a very strange problem and I'm not sure whether it's a bug.


[TestMethod]
public void WindowNatualMockTest()
{
using (RecordExpectations r = RecordManager.StartRecording())
{
System.Windows.Window win = new System.Windows.Window();//[1]
}
}

When I run it the following error occurred at location [1].
Error Message:
System.Reflection.TargetInvocationException: --->
System.TypeInitializationException: --->
System.Window.FrameworkElement: --->
System.TypeInitializationException:
Error Stack Trace:
System.Windows.Freezable.Freeze(Boolean isChecking)
System.Windows.Freezable.Freeze()
System.Windows.Media.Transform.MakeIdentityTransform()
System.Windows.Media.Transform..cctor()
System.Windows.Media.Transform.get_Identity()
System.Windows.FrameworkElement..cctor()
System.RuntimeFieldHandle.GetValue(Object instance, RuntimeTypeHandle fieldType, RuntimeTypeHandle declaringType, Boolean& domainInitialized)
System.Reflection.RtFieldInfo.InternalGetValue(Object obj, Boolean doVisibilityCheck, Boolean doCheckConsistency)
System.Reflection.RtFieldInfo.InternalGetValue(Object obj, Boolean doVisibilityCheck)
System.Reflection.RtFieldInfo.GetValue(Object obj)
TypeMock.Mock.a(Object A_0)
TypeMock.Mock.d(Object A_0)
TypeMock.RecorderManager.a(String A_0, String A_1, Object A_2, Type A_3, Boolean A_4)
TypeMock.RecorderManager.a(String A_0, String A_1, Object A_2, Object[] A_3, MethodBase A_4, Object A_5, StackTrace A_6)
TypeMock.MockManager.a(String A_0, String A_1, Object A_2, Object A_3, Boolean A_4, Object[] A_5)
TypeMock.InternalMockManager.getReturn(Object that, String typeName, String methodName, Object methodParameters, Boolean isInjected)
System.Windows.Window..ctor()

I tried using the Reflective Mock and mock successfuly.

[TestMethod]
public void WindowReflectiveMockTest()
{
MockManager.Init();
System.Windows.Window win = MockManager.MockObject<System>().MockedInstance;
//...
MockManager.Verify();
}

Environment as follow:
<<<<Microsoft>>>>

Any help will be great appreciate.

chris