1. Quit Avid Media Composer (if open)
2. Go to this location:
C:\Users\Public\Public Documents\Avid Media Composer\Settings
3. Back up then delete these files: – MCState – Site_Attributes – Site_Settings
4. Close all folders then re-launch Media Composer.
https://avid.secure.force.com/pkb/articles/en_US/troubleshooting/en259893