If you have a Windows XP desktop computer and you try to shut down your machine from the command-line by typing shutdown -s then you may get the following result in response to this command:
The operation completed successfully.
A required privilege is not held by the client.
This will happen if you are logged on to your machine as an ordinary (domain) user instead of an account having administrative credentials. This happens because of a bug in how the shutdown.exe command works in Windows. Fortunately, there's a workaround:
1. Log on as an administrator and open Local Security Settings from Administrative Tools.
2. Select Security Settings \ Local Policies \ User Rights Assignment
3. Open the user right named "Force shutdown from a remote system" and add the INTERACTIVE group to this user right.