New Post: Getting COMExcpetion when attempting to register changes in a Windows 8.1 PC

I'm not sure what is causing your error. I would change your code sample to:

Using D as New TaskEditDialog(ts.GetTask("\MyTasks\Task1"), True, True)
   D.ShowDialog()
End Using

Let me know if that changes anything. I had tested this on 8.1. If you are seeing the error still, please post the result of the D.Task.Xml after calling the constructor (or Initialize) but before calling ShowDialog.