With a looming virus attack being reported in the media, I spent Friday AM updating my primary work PC running Windows 2000 server, which is also the only computer on my home office network attached to the Internet. I installed Windows 2000 SP4 and being too confident from successfully installing previous W2K Service Packs, I did not archive my SP3 setup.
SP4 knocked me right off the Internet and screwed-up local LAN access as well. My IT guys at HQ in Pittsburgh are still in the process of getting the MSDN W2K3 CDs to me here in Vermont (thankfully) or I would have upgraded the machine to W2K3 Friday afternoon instead of sitting on the problem and mentally working through it. A W2K3 upgrade would not have fixed the problem anyway.
Today, Sunday, I am happily back online and my W2K Server is working great with SP4. The problem was good ol' McAfee with a possible secondary culprit being my ZoneAlarm firewall software. I uninstalled both, and for good measure, uninstalled all Internet Information Service components, as well. (I never use IIS on this machine.) I reinstalled SP4 and am once again a happy Microsoft Developer.