When your original install of Win2k was configured to always assume the same user was logging in thats where you get stuck. Upon installing SP4 the user profile becomes corrupt and you dont get a chance to swith users because thats the way it was initially configured,.. to assume. So you have to F8 during the boot to get to boot options, select safe mode with command prompt. On the command prompt screen type in explorer.exe. Log off widows and log back in as Administrator. You might want to set the administrator password in control panel first if you are not sure what it is... and set windows to require a password. After you log back in as administrator Copy your important files from the documents settings corrupt user profile so you dont lose them. ie.. favorites, my documents, pics etc.. Then Delete the corrupt user profile file under documents and settings ... reboot and it should make a new profile folder for that user upon login. If not then follow the steps above again, but go into control panel users and create a new user, delete the old user and log in as the new user.
I know its like 8 years late, but maybe this will help someone.
