After connecting my DJ controller to the computer (one that already has it's on sound card built in) via USB, my MBP no longer recognizes its own audio card. It does not show up under system profiler, either. When I press sound buttons on the MBP, it shows up with an X. The only way the sound works now, is through via USB to an external audio card. Which is annoying because the only thing I got is a mixer, which then hooks up to an even bigger sound system that I don't lug around. And FYI, the headphone outlet doesn't work either if it's plugged in there. I took it to the APPLE STORE, they tried rebooting it from OS from an external hard drive, that didn't work. I tried reinstalling OSX, that doesn't work either. Any similar situations/ideas/solutions can you guys help ?