Your critical updates are up to date ?
If so either disable ‘IPSEC Policy Agent” from Services.
Or Uninstall ‘Windows 2000 Hotfix KB835732’ from control panel. If its that slow start in safe mode to do these tasks.
This is a known problem in some pc. (i.e. Dell & Compaq laptops)
If you can’t live without update MS04-011
http://support.microsoft.com/default.aspx?kbid=841382 upgrade to Windows XP.