I had the same problem with my SCSI zip 100 drive here. I can't remember what I did to fix the problem because this was over 2 years ago. I'm guessing it was a problem with the options in /etc/fstab. Take a look at my fstab entry and see how different this is from yours.
Code:
/dev/sdb4 /mnt/zip auto noauto,owner,kudzu 0 0