This is for anyone who's using the AutoLogin greasemonkey script and is thinking about changing his password.
If you're going to change your password for whatever reason, remember to disable the AutoLogin script before you change your password. To disable it, right-click the red smiling greasemonkey icon, and left click the AutoLogin script. Change your password. Logout of CC. Log back into CC manually. Re-enable the AutoLogin script by right-clicking the red smiling greasemonkey icon, and left click the AutoLogin script.
If you don't disable AutoLogin before you change your password, and something happens to cause you to need to login again (session timeout, or closing your browser for instance) then AutoLogin kicks in and tries to log you in with your old password (repeatedly). When this happens a login security mechanism kicks in and makes you wait 30 minutes before you can attempt another login.