If you've imported media from another version or catalog tapes, they automatically get associated with the "imported media" set. You need to get them out of there since that media set is configured for infinite DON'T allow overwrite AND append. So, if you try to do a backup after importing some new media and try to use the same tapes then that's when you'll get the dreaded V-79-57344-33037. Create a new media set and set the overwrite protection to your liking and then set the append period to infinite. 
Madur0
Madur0
