My M-Audio USB controller just inexplicably stopped working in Logic Pro X as well. It worked fine for 2 years. I went to add a track into a song and the keyboard just stopped responding!! I am running Mavericks on a 2013 MacBook Pro. Did I change a preference or hit a button that disables my usb keyboard?? The Musical Typing keyboard popped up. That works fine but now I can't finish my project!! Please help. All the Google and YouTube stuff is for configuring a MIDI controller. Is this a simple fix?? I see these other posts are from 2009! So I am really worried.