I recently lost audio output from my MacBook Pro. As usual, I had been fiddling with several things at once so don't know how or if I triggered the issue. I had been dealing with Airtunes problems but assumed network issues. I had also been trying to mount NTFS volumes with MacFuse and NTFS-3G but had compatibility issues with Lion. Looking in the Sound control panel, Audio MIDI setup and System Profiler, no internal output option was available. I did have SoundFlower and Digidesign options. While troubleshooting this, I noticed that only the frontmost of the three USB ports on the MBP was working. I booted into Snow Leopard from an external drive and everything was working fine. Researching the issue, a reference to 32 vs 64 bit got me thinking, so I booted into Lion in 32-bit mode and everything worked again. Back into 64-bit, no audio, only one USB again. I've removed the SoundFlower and Digidesign stuff (incompatible with Lion anyway) and the NTFS stuff without effect. Can anyone advise me where to look next? I've browsed the logs but don't really know what I'm looking for. Any help would be much appreciated.