We have purchased some new tapes. They are the same as the old ones. All are Verbatim 4mm-DL 90M. When a new tape is inserted, it is ejected after about 10 seconds. If I write protect the tape, it is accepted and can be inventoried. It shows up as a blank media(write protected). The old tapes still load just fine. I get the same results with NT Backup. There is a slight mechanical difference between the new and old tapes. On the bottom of the cartridge, the plate that slides to expose the drive holes has deep cut outs on the old tapes, but almost nothing on the new tapes. The configuration holes along the front of the cartridge are the same on the new and the old.