external USB hard drive

The hard drive was connected to Redhat9 Linux via firewire and the hard drive had a reiserfs filesystem. It was supposed to be used for backups, but suddenly stopped working (it was not anymore recognized during system startup). Probably that had something to do with the external USB zip drive. Both are apparently visible to the system as SCSI devices and the zip drive might have (via automount) occupied the sda number that was manually added to /etc/fstab to enable the Maxtor hard drive. To check whether everything is OK with the drive itself, I connected it to my work computer.