I have the same problem!  We adopted a three-year old female, who lived in a
country house.  She was known to hunt mice in the walls.  Things are less
exciting for her at our place.  She loves the dog (a huge Golden Retriever)
and the cat, but she cannot abide other carpet sharks.  What she has against
her own species, I don't know!  I have tried to leave them together for
short periods, but I think one will be killed if they are together too long.
I have tried smacking her nose, spritzing them with water, holding them
close but not in biting range, switching cages between the different
ferrets, etc.  Short of Valium, I am stumped.  Incidentally, the other
ferrets no longer trust her, so the problem is two ways now.  I am hoping
that our young male, who is easy-going and utterly fearless/senseless, will
be able to hold his own when he reaches full size.  For now, she is the only
thing he avoids.
[Posted in FML issue 2088]