"other" in Network Devices <?>

Hi,
I am setting up a home network with two desktops and a
laptop. The server desktop (desktop1)and laptop have been
networked for a few days just fine. Tonight I added
desktop2 to the network. On this desktop2, in the MBN
utility screen I don't get the same little computer icons
with the destination/device names as with the other two
computers. This one shows a different icon and
indicates "Other Device" and the IP address. When I click
on it, I get a screen indicating no device information is
available.
I have file sharing on the other computers, and they can
access each other just fine.
What causes this and how can I remedy it so I can share
files with this computer???
Thanks very much-
George