>The Error -2817 or -2807 message refers to the absence of a shared library in the System Extentions folder. This could be caused by using an system software earlier than 7.5.3 on a Power PC Mac. If you are using 7.5.3 or later, the error message probably only means that the SOMobjects or Shared Library Manager extension is not active. Try restarting the Mac with the Base OS Extensions active in addition to the following:FreeMIDI System Extension, FreeMIDI Power Plug, Shared Library Manager, Shared
Library Manager PPC, SOMobjects, Sound Manager, and the MOTU folder. Serial Tool and/or Serial (Built-in) should be active as well.

see topic: Improving MOTU Audio System Performance - Extensions