Event ID: 341 (Failed to load Symantec Premium AntiSpam engine) or Event ID: 514
Conflicts with licenses in the Licensing folder
Backup and remove all license files (*.slf) from the default licenses folder (c:\Program Files\Common Files\Symantec Shared\Licenses)
Re-install your currently valid license from the SMSMSE console (Admin >> Licensing >> Browse and "Install")
Disable and re-enable Premium Antispam (Policies >> Premium Antispam Settings >> "un-check" Enable Premium Antispam and deploy changes, then "check" Enable Premium Antispam and deploy changes)
Review Windows Application Event logs and confirm that the errors are no longer appearing.
Windows 2003 / Exchange 2003