Total Garageband newbie. Got my keyboard hooked up. In the "Classic Organ" mode, notes randomly get "stuck" - they continue to play after the key is released, even after the keyboard is turned off. This happens very often, and very randomly. In the "Electric Piano" mode, notes will randomly get sustained (same as organ problem, but notes fade as opposed to sustaining indefinitely). In "Grand Piano" and "Smokey Clav" mode, it seems to play fine. Weird. I've googled & searched online and not found much of anything. The hardware/software: Mac Mini, OS 10.6.8 GarageBand '09, version 5.1 Yamaha PSR-500M keyboard Midi cable plugged directly into Mac Mini Thanks very much for any help!