Make sure you have followed the proper setup procedure for using OMS and Motor Mix with a MOTU USB MIDI interface (see the Motor Mix FAQ).The use of the HUI or Motor Mix and OMS (required for Pro Tools) in conjunction with a Mark of the Unicorn USB MIDI interface has in some cases proven to be unstable, and resistant to trouble shooting. If your are experiencing these sorts of problems, try using another brand of USB MIDI interface, or switch to using the interface's old Mac Serial port if it is equipped with one. Problems are more often seen when using multiple HUIs or Motor Mix units, so also try using only one controller if possible.