Welcome to the MPV forums...
In order to help it'd be useful to know more info on your setup:
â€¢ Version of Logic
â€¢ Version of OS X
â€¢ Do you have the latest drivers from M-Audio?
â€¢ Are you running Logic in 32-bit or 64-bit mode?
â€¢ Have you done any basic Mac maintenance (e.g. repair permissions/restarting, etc?)
â€¢ Have you tried using a different USB cable?