I'm on Mac Leopard, NUDC 5.3.1 on MacBook Pro and as of about two weeks ago am having an issue connecting to our Contact server (am having no problem with the Event server). My husband is on the same network, he's updating just fine. I can't get past "Looking for Server". When I first launch I see a brief "sending edits" then back to looking.

The thing is, I know my Mac at least "sees" the server, because I can look at the public categories, add/change/delete them, etc. The server just ain't seeing me back.

I've tried:

Rebooting my system completely (including modem/router)
Reinstalling software
Upgrading to yesterday's 5.3.2b
Repairing disk permissions
Doublechecking firewall issues (though since my husband on same network is okay I don't see that as the issue)
Using both airport and ethernet connections
Doublechecking all my network preferences
Kicking everyone's connections off the server (didn't see one for me however)
Moving some contacts from public to private and back
Setting up a new contact file (but can't do that because it says I can't connect to the server)
Stopping/restarting server
Sacrificial offerings

All to no avail.

Right before I stopped syncing I moved a couple hundred contacts from one category to another. These have successfully synced to the other users.

Any ideas? I'm going nutty.

To add to what I've tried:

Getting on my husband's wireless access point
Closing Contact, trashing all related prefs and restarting

The test category I created is showing up for everyone else, but not any updates I've made to records or test records I created yesterday. Notes don't always show up for other users either but that's been a chronic problem the whole time we've used NOW unfortunately.

Try copying a contact file from one of the other machines, and opening it on yours. The inability to connect using a new file would seem to indicate something is either blocking, or at least not forwarding, the connection from your machine to where the contact server is. Any recent hub, router, or firewall changes? Hardware or settings?