ODBC problem - see out, but cant see in

Windows 2000 Advanced Server (latest service pack)
SQL Server 2000 Enterprise Edition (8.00.2187)

1. Server can see other machines in network through Windows Explorer
2. Server can connect to other machines in network through ODBC
3. Other machine can't connect to my server through ODBC
4. Other machine can browse shared folders on server through Windows Explorer
5. Worked fine yesterday, ODBC went out sometime before midnight last night
6. No events pointing to problems in the event log.
7. Problem is fixed with reboot.
8. Automatic updates is turned off
9. All updates were downloaded and installed about 1 1/12 weeks ago.
10. Server can be seen through Enterprise manager on server
11. Query analyzer cannot connect from remote machine
12. Query analyzer can connect if ran from server

What should I be looking for to make sure that this doesn't happen again? (I know that there has been more updates since then)You don't have DHCP turned on on the server, do you?|||Just client not server. This machine isn't a domain controller. It logs into another domain and isn't part of a cluster.|||On point 7, which machine (client or server) is rebooted to fix the problem? Also, can you check on the server using the Server Network Utility tool to see what protocols are supported there, and in what order? Do the same on the client using the Client Network Utility (cliconfg.exe, if it does not show up in Programs). Also check for aliases on the client (same utility, different tab).|||Server rebooted to fix problem.
Server - Only protocol enabled is TCP/IP.
Server - No aliases.
Client - TCP/IP & Named Pipes
Client - No aliases.|||Next time you get the error, check the exact wording of the message. If possible post it. I am out of ideas for the moment.

There are no firewalls, or other filtering devices between the two machines, right?|||It worked fine till last night. I haven't applied any hotfixes to SQL server in months.

The error was the same one that you get when you type the name of the server wrong or put in the wrong password - 'Server does not exist or access denied'.

I can't verify it, but I think some network 'tweaking' has been happening in the area. I can just blame it on the network guys, but I need to be sure that there's nothing wrong with my server.|||I can't find anything wrong with my machine. Everywhere I looked pointed to a problem with the firewall or a network problem. Since the reboot fixed everything and I haven't seen a problem since I am going to assume that there was some firewall changes or something like that.

Thanks for all the help everyone gave. Hopefully this problem will not come back.|||Did you try creating an Alias?

Could be a DNS thing