XP computers not showing in Network Neighborhood

[fdv]

Windows 2003 running DHCP, Active Directory, WINS.

5 Windows 2000 boxes, 2 Windows XP boxes.

The computers all have their drives shared, printers too, and file and print sharing is on.

The XP computers have traditional networking switched on, that is to say, the ForceGuest setting in the Registry is zero.

May or may not be significant: at the moment, in the interest of expedience, the XP machines have blank passwords.

The Windows 2000 computers and the 2003 server show up on ALL Network Neighborhoods. The XP computers do not show on ANY Network Neighborhoods, not the server's, and not even their own. There are no conflicts, no error messages, all machines are updated to their current patch level (XP=SP2+all post hotfixes to Nov, Win2k=SP4+Rollup+all post hotfixes to Nov).

NetBEUI is not installed on any machine, FWIW (I understand it doesn't need to be, I'm just throwing that in). AD is properly configured and the XP machines show in the list of AD resources in the user list. The XP machines are reachable if one manually types the UNC pathname in the Explorer bar, such as \\XPmachine1\drivec etc. The machines were not configured with anything screwy, like Registry settings to disable administrative shares or anything like that.

I have searched around for this but I find only obvious cures that don't apply to me (i.e. bad NICs, TCP/IP misconfigured, no netbeui with Win 98 machines on the network, wrong workgroup or domain name, etc. None of that applies.)

Any help is most appreciated.

[spacesurfer]

Try installing Link Layer Topology Discovery protocol (http://www.microsoft.com/downloads/details.aspx?familyid=4F01A31D-EE46-481E-BA11-37F485FA34EA&displaylang=en) if it's not already installed.

Without this installed on XP machines, XP machines do not show up in Vista and installing this update solves the problem.

Maybe this will also work for 2003.

[nitroshift]

Make sure you have UPNP devices set to be shown. I encountered the same issue and that solved it.