FSX Crashes after installation

[hezza54]

I have used FSXWX trouble free for about a year (thanks). Running 1.5.1 on FSXSE and Win 8.1
Recently there have been random crashes like the above. Windows reports unhandled .NET exception in FSXWX. Takes FS down with it.
Sometimes though there is no problem.

System.Runtime.InteropServices.COMException (0xC000014B): Exception from HRESULT: 0xC000014B
at System.Runtime.InteropServices.Marshal.ThrowExceptionForHRInternal(Int32 errorCode, IntPtr errorInfo)
at Microsoft.FlightSimulator.SimConnect.SimConnect.ReceiveDispatch(SignalProcDelegate pfcnSignal)
at Microsoft.FlightSimulator.SimConnect.SimConnect.ReceiveMessage()
at FSXWX.Form1.DefWndProc(Message& m)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
at System.Windows.Forms.ContainerControl.WndProc(Message& m)
at System.Windows.Forms.Form.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)