This is not the stock result of how Windows 2000 installs and configures itself. I usually see this when someone either had Spyware/Virus/Trojan issues or went to BlackViper's web site and disabled too many services.
The fix is never the same thing, but the story about how one put Windows 2000 into such a condition helps to find what ails this issue.
For now you can just run Windows Update.
The Automatic Updates window is all greyed out
and I don't have any update service available in the Services list (not even disabled ones).
I've reinstalled SP4 but it didtn't fix it.
What can I do?