Mac OS X 10.2: Cannot Change Account Settings of Logged-In User Until You Type Password

Admin users can edit the accounts of other Admin users without having to re-enter their passwords, known as reauthentication, but they must reauthenticate to edit their own accounts.
Symptom

You go to the Accounts preference pane, select your own account, and click Edit User. All settings other than the Picture are unavailable for editing (dimmed). The dimmed settings include the checkboxes for "Allow user to administer this computer" and "All user to log in from Windows".

You may notice that the Lock button, which normally indicates when you need to authenticate, already appears open.

Only after typing your password do the settings become available.

Solution

Type your password in the Current Password field and press Return to make changes.

The appearance of the Lock button is misleading in this instance, and the authentication is inconsistent.
Published Date: Feb 20, 2012