Previous versions, if we renamed the service that Mezzmo ran as, for instance mine is called 'RhaeVision', when you upgraded Mezzmo, it would error out and not start/restart the service saying that the service was unavailable. I mentioned it in a thread quite a while back and you fixed that. It's back again. 6.0.0.0 had the same "service unavailable" message.
Bookmarks