On OS X you may encounter the following error message on startup:
[B0011] User “<username>” lacks sufficient permission to run Synfire Pro <version>. It is required that you are a member of the “admin” group, or have the software installed specifically for <username>. The program will exit now.
This indicates the file permissions for the folders /Library/Application Support/Cognitone and/or /Library/Application Support/Synfire Pro (or: Harmony Navigator 2) have been messed with and need to be fixed. We don't know why this happens in the first place, probably some other software's installer that modified the folder's file attributes.
The solution is to manually uninstall Synfire/HN2, as explained here. Then run OS X Disk Utility to "Repair Permissions" on your startup volume. After reinstalling Synfire (or HN2), the problem should be fixed.