Could there be a reason that SmartWare doesn’t recognize a WD DL2100 on the network as a backup target from one computer (Server 2003) ? Smartware on all the Win7 workstations can backup to the DL2100
It does recognize an attached USB drive on the server
Have you checked the anti virus and firewall on the server computer to see if the drive is being blocked? Also i would like to know if you are able to see the network device on the computer.