Garageband Problems

When I attempt to load GarageBand version 4.1.1, it will begin initializing as normal, however after approximately 20 seconds, the "CoreMIDI Server.framework" folder begins popping up into the dock for a brief moment (maybe 2 seconds) and then disappears. This will go on for a few minutes before the message "Garageband detected possible conflict with one or more third party MIDI or audio devices." If Garageband ends up actually loading, the warning "Mac OSX MIDI devices are not available." This warning will continue to pop up if I attempt to use Garageband. The CoreMIDI folder continues to pop up, even if Garageband is quit.