[zappity]

I'm chiming in here in the hopes of saving you some time.

I'm running PT 9.0.6, Mbox Pro 3, on OSX 10.6.8

Recently updated my Mbox driver to 1.2.2 but then kept getting "Pro Tools hardware is either not installed or used by another program" error messages. I could not get Mbox to show up as the Current Engine in the Playback Engine window (only saw Pro Tools Aggregate I/O). Upgrading directly to 1.3.0 from 1.2.2 did not work. Neither did uninstalling the driver and just installing 1.3.0

Here's what worked for me on my set up:

Download and install 1.1.5. Then, without uninstalling, upgrade to 1.3.0 directly. Restart and cross your fingers.

I hope this works for you. But wanted to let people know that I was able to get the most current Mbox driver working with Pro Tools 9.

Good luck