Error -618 occurs normally because there is a mis-match between versions of FreeMIDI Sytem Extension and FreeMIDI Power Plug. This may happen if FreeMIDI files were dragged from one hard disk to another. To remedy the problem, we recommend deleting FreeMIDI System Extension and FreeMIDI Power Plug from your System, downloading the latest FreeMIDI from our web site downloads page, and reinstalling the latest FreeMIDI.