Macintosh 9.x can no longer access 2000 server

[ddamm]

We have a stand-alone Windows 2000 server that has shares that have been accessed successfully by Macintosh (OS 9 and OS X) and PCs for the past year, until today. All of a sudden, the Macintosh 9.x computers can no longer connect to the Win2K server. The PCs and the Mac OS X computers are not having any trouble connecting to the server and accessing the shares. I have checked the following on the 2000 server:
1) Virus scan did not turn up any viruses
2) Spyware scan using SpyBot, Adaware, and HijackThis - some spyware and adware was removed. There was nothing suspicious in HijackThis.
3) Installed missing Windows Updates
4) Rebooted the 2000 Server a couple of times
5) Stopped and restarted File Services for Macintosh
6) There is nothing in the error log to indicate a problem with the shares or with Macintosh services
7) All the permissions for the shares appear to be unchanged
8) The server is dual homed. The NICs are in good working order as evidenced by the PCs & Mac OS X computers being able to connect to the server.
9) I removed File and Print Services for Macintosh, and reinstalled them. Then I recreated the shares (both PC and Mac). The Mac OS 9.x computers still cannot connect to the server. Although it does appear in the Chooser.

This problem is urgent and inhibiting work. We have burned working files to cds as a temporary work-around. Any suggestions would be welcomed.
Thank you in advance.
--David