Did you email support@larian.com, as well? It is the middle of the night there now, but hopefully they will be in early tomorrow.
There should not need to be a D2:ED patch installed before installing FoV, or you'd think that would have been clearly stated in some install notes, or a warning given when installing the add-on.
What version of D2:ED do you have? I assume English, but what region, and DVD or digital download?
