May I suggest that the INVITE function be available to at least admins permanently?
It's an incredibly useful and powerful feature to encourage registrations, case example, if you pick up a few emails while out networking or have a mail database you'd like to use to drive users to your forum.
I already re-installed onto a new server. I was only testing .. If I do reproduce I will make sure to provide stacktrace. I do appreciate you looking into this. I will make sure in the future that I can provide more details.