We installed a Seagate tape drive using Travan NS-20 tapes about 18 months ago. Kicked off with 10 tapes, rotated fortnightly. Now I am down to 6 tapes as the others have read errors. This seems excessive as 30-odd uses per tape is not much. Is this normal or could it be dirty heads? The tapes that have been put aside as duds tested 'bad' 2 or 3 times, not just once. System" Win2000 Server and NTBackup.