I'm using an MBox Pro with Pro Tools 9.0.6 on a Mac running the Lion OS (10.8.2). I have found PT9 to be pretty buggy. My latest problem is that when I record-enable a track, I get loud feedback coming through the computer's internal speakers. I have made sure that I've chosen the MBox for input and output in my Mac System Preferences. I re-downloaded and re-installed the appropriate driver from Avid. Does anyone have a clue as to what might be wrong? Thanks.