I had almost the exact same issue. I installed the lipo 64 version. Everything is happy now!

--- In firebird-support@yahoogroups.com, "johnryh" <johnryh@...> wrote:
>
> Using Firebird 2.5.1 on Lion 10.7.2 on a 4 core machine I attach to 2 separate databases on the same machine in quick succession via localhost. Firebird always opens the first database with no problems but often hangs opening the second database. The only way out is to reboot repeatedly until it does work. It then continues through the session to attach without error to both databases repeatedly whenever my program is re-started. On shutting down and later reboot it often hangs again. Debugging shows my program stops on calling isc_attach_databaseType. System logs show nothing that I can see as relevant.
>
> I have tried all 32/64 versions of Firebird for OSX except the lipo version and they all exhibit the same problem in Lion but work without problems in ms windows and in Snow Leopard.
>
> Any ideas?
>