Mbox 2 in use by another application - OSX 10.3.9

[Athenor]

Good Afternoon.

I work as tech support for a small church, and my boss is an avid user of ProTools LE with an Mbox 2. Two days ago, an issue arose which I cannot seem to find an answer to.

When one starts up Pro Tools LE 6.8.1 (yes, he knows he needs to upgrade), a pair of error messages appear. The first happens before anything is on screen:
"InitMachOEtherIPCShim failed. Error: -1501"

Then, when you click the OK button, the splash screen for Pro Tools comes up. When the bottom says "launching DAE" and the loading bar is about 1/10th of the way across, a second error message appears:
"Digidesign hardware is in use by another application. (-1133)"

The only other application running is finder. We have done multiple restarts, and I've tried cleaning up, authentication, and everything short of completely uninstalling and reinstalling the program, as my boss has the disks for that.

I've done multiple searches looking for help with my issue, as well as about half the general troubleshooting page and an upgrade of the mbox 2's firmware to 1.38, to no avail. Thus, I am posting this in hopes that someone can recognize these issues and explain where to start hunting for a solution. I'm about 70% familiar with a mac (I can't move through it and see where things are like I can with a PC, but I'm starting to see the logic of its folders and associations), and any help that can be given would be greatly appreciated.

Thank you in advance.