That's a problem in the scripting, it was present in the CVS version and I think early versions of Z's 3D version.
It's fixable on the client side, the valdemar rates are ramped up out the ass and hardly anything else spawns. As I recall, it's in the items script file, just figure it out yourself or wait for someone that remembers better than I.
Note "control" only means that you'll be able to choose not to turn into a werewolf when it prompts you, you aren't able to turn whenever you want with that amulet.