NullReferenceException: Object reference not set to an instance of an object.
StackTrace:
   at System.Windows.Input.WispTabletDevice.CreateContext(IntPtr hwnd, PenContexts contexts)
   at System.Windows.Input.StylusWisp.WispTabletDeviceCollection.CreateContexts(IntPtr hwnd, PenContexts contexts)
   at System.Windows.Input.PenContexts.Enable()
   at System.Windows.Input.StylusWisp.WispLogic.EnableCore()
   at System.Windows.Input.StylusWisp.WispLogic.OnTabletAdded(UInt32 wisptisIndex)
   at System.Windows.Input.StylusWisp.WispLogic.HandleMessage(WindowMessage msg, IntPtr wParam, IntPtr lParam)
   at System.Windows.SystemResources.InvalidateTabletDevices(WindowMessage msg, IntPtr wParam, IntPtr lParam)
   at System.Windows.SystemResources.SystemThemeFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)