This is a very strange issue. Maybe Micheal will have an idea.

I have tryed to think of everything I can to get to the bottom of it.
Like you, now thinking its a Firefox issue of not releasing our password since its our password its holding.
I am now wondering if a new person on a different who is using Firefox sees it or not since they havent been there before and saved the password. ?
UPDATE: Chuck I went to a neighbors computer and went to register and the encrypted password place was blank using Firefox.
This means its our Firefox saved passwords that is showing and I guess its not really an issue since New members will not see the encrypted passwords as we do.
Seems its something all the time trying to narrow down issues and problems.