To disable the Task Manager in Windows 2000, click on the Start button and select Run. Type in 'regedit' and press OK. Now look for this String:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\
In the right pane, right-click on an empty space and select 'New->DWord Value' then name it 'DisableTaskMgr' and press Enter. Now, right-click on the new value and select 'Modify'. In the 'Value Data' box, change the 0 to a 1 and press OK. Restart your computer for the changes to take effect. To re-enable the Task Manager, change the 'Value Data' back to 0.