I bought an external Hard drive for my macbook pro to use to work on all my protools sessions on. After transferring all my sessions to the external drive and opening up a session, I get no sound coming out of my speakers. Protools is working properly, all meters are working, and protools is working as if nothing is wrong with it. I thought something was wrong with my settings for my interface(m-audio firewire solo), but there still isn't any sound coming out. I took all my files out of the external drive and transferred it back onto my macbook pro and now sound is coming out of my speakers. I can't figure it out. Do you think it's the external hard drive? Should I get a new one? Can anyone help???