If you initially create your project using a MIDI device and later replace it with a new one, you will receive an error message from LiveProfessor when loading the program, indicating that a MIDI device is missing. This is because MIDI hardware is identified by its name.

To resolve this issue, open the MIDI Device window by navigating to Options > Audio & Midi Options > Midi Devices, and click the Hardware Device column for the missing device. From there, choose the new hardware device you want to use.