In some cases, FreeMIDI updates accidentally install a second "MOTU USB FreeMIDI Driver" instead of just replacing the old one.

Inside the System Folder, locate and open the FreeMIDI Folder. Inside this Folder, look for "MOTU USB FreeMIDI Driver" . If there are more than two, drag the older one into the trash.
Typically when this happens, the two drivers are named:

- MOTU USB FreeMIDI Driver
- MOTU USB FreeMIDI Driver 2.0

Trash the driver that is NOT labeled "2.0"

Restart your computer, and try launching FreeMIDI again. If the problem persists, try:

1. Create a new FreeMIDI configuration.
2. Trash all FreeMIDI items in the Preferences folder (inside the system folder), and restarting once more.
3. Reinstall the latest version of FreeMIDI, trashing all related items first.