It seems that the recent TCP/IP fixes for Windows did not extend to Windows 2000 Server.

http://news.techworld.com/operating-...old-to-update/

Earlier today, Microsoft delivered five critical updates that patched eight vulnerabilities in Windows, including one that the company won't bother fixing in Windows 2000 Server SP4. The operating system's support doesn't end until July 2010; until then, Microsoft was supposed to provide updates.