Hi, Roy. It has been a very very long time since I have used a zip drive since I use a cd burner, but I seam to remember you need to load generic scsi support and I believe there is a specific module for the zip drive you need to load in /etc/modules.conf. Try looking at the kernel docs. To see which modules need loaded. I'm afraid I won't be of very much help, because I no longer use zip drives, and forgotten how to set them up under Linux.
