How can I remove the Shut Down button from the login screen?

A. To remove the Shut Down button, start the registry editor, go to the HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionWinlogon subkey, and change ShutdownWithoutLogon from 1 to 0.

You can use the policy editor (poledit.exe) to accomplish the same task. Expand the Windows NT System - Logon tree and clear the "Enable shutdown from Authentication dialog box" setting.