MacPro with OS 10.4.9 had been working just fine accessing other Macs over the network. One day, the MacPro lost it's "Network" icon in the left column of the finder windows and shows no "servers" under the "Go" menu, "Network" (shift-command-K) option.
I can access the MacPro from all other machines on the network, it's just the MacPro that doesn't see the other macs.
I had tried and tried to change the Network settings through the System Preferences... never even realizing that the Finder has it's own preferences available through the Finder menu.
Somehow the "Network" icon had been unchecked in the finder prefs. I checked that and SHAZAM... there it was. I clicked on the newly restored Network icon in my finder window and up popped all the machines on my Network.