NT Backup Error Message

Suddenly for no apparent reason all my backup tapes render an error message,
“unrecognizable data”. I can’t find anything on this in the Microsoft Knowledge base as to what might have happened. Has anyone else had this happen and what had to be done to fix it. Right now we don’t have another tape drive to swap it with and it’s a new device that was working only a few days ago and appears to still be working. The power and drive cables are undisturbed also.