If Garritan Personal Orchestra is installed on workstations using NFS home directories, it may require different license keys. These are generally stored on each workstation in '/Library/Preferences/GARRITAN PERSONAL ORCHESTRA.plist'). Starting Garritan works just fine for any regular user, but Garritan then creates the file '~/Library/Preferences/GARRITAN PERSONAL ORCHESTRA.plist' in which it copies the licensing information (including the hardware key) for the version installed on that machine.
This has the side effect that if the user logs out and logs in on another machine and starts Garritan there, it will claim that it is not licensed (since it finds another machines key in the preferences file).
Removing the file '~/Library/Preferences/GARRITAN PERSONAL ORCHESTRA.plist' then allows you to start Garritan on that machine as well.
Native Instruments (which handles the licensing for Garritan) confirmed this problem, and admits there is at the moment no bugfix available.
Lines added to /Library/Preferences/com.apple.loginwindow.plist:
March 6, 2006