I think since FF17 I have the following issue, which I could find no references anywhere: = It is a shared computer (5+ users) with latest Mac OS X 10.7.* installed = There is an administrator account and several users = Every time FF is re-installed (remove/install) it works fine for all users = Right after FF upgrade (during about a day?) itself, it is only working for administrator (or user from which upgrade was initiated) = For all other accounts the application does not work any more (from any place, link or Application folder) = When during this "problem time" with any other user I do "Show Package Content" and double-click "Updated.app" inside, Firefox started without issues. = Also no issues seen with any of these users if I just copy Firefox.app to user folder and start. But then the temporary "Updated.app" is removed somehow.
To my understanding there is a "post-install" task in Firefox update procedure, which, somehow, only works for Administrator user (or FF application owner) and not for any other user.
May be the "update" process was designed such, that "Updated.app" is not compatible with Mac OS X security model, when regular users have no update rights/permissions on Firefox.app
This is, indeed, a pretty recent FF issue (month or two).