E6300 errors were only solved when I replaced the tape drive (Sony SDX-400c). I had upgraded the firmware, Arcserve had exclusive access, was using the Adaptec's, Sony's drivers for the SCSI, Tape drive. New tape drive also solved problems of several "bad" tapes. Took three sessions with Sony though. Quick test- unplug the data cable, boot up your computer with tape in the drive- If the busy light goes on again after the inital check- your drive is bad.