Hi Barry,
Check to make sure you don't have a lot of temporary files in your Catalogs folder. Navigate to the following locations:
C:\Program Files\Symantec\Backup Exec\Catalogs
C:\Program Files\Symantec\Backup Exec\Catalogs\<ServerName>
Make sure there are no files with the extensions: .TMP; .SM; and .FDD present. If there are more than a dozen files, it could be causing problems.
If the files are there
-- stop all Backup Exec services
-- delete files with the extensions: .TMP; .SM; and .FDD
-- restart all Backup Exec services
-- inventory and catalog all pieces of media associated with that backup job