Colorado SureStore T4000 under NT 4.0 Server

[Julia Hardy]

We are running NT Server 4.0 with Colorado T4000 for a scheduled full backup (Monday night) and incremental (Tues-Thur)nights. Frequently, the backup fails with an error message "Changer Timeout". We reboot the server and manually run the backup in the morning. It works. This of course is not ideal!
We also get a non recoverable hardware error - 04.40.66 and other error messages from time to time.
Has anyone experienced the same problem? We have changed the tapes and used new ones to no avail.
Thanks