It is common for people who have old cookies saved on their computer to become persistant cookies if the website's cookie settings get changed while the old cookie is still active. This may prevent a user from properly logging out.

Clicking any "logout" link throughout the site will clear all cookies and log you out of the site. If you click a logout link, but you remain logged in, you may need to clear your cookies manually. Please consult your browser documentation for instructions on manually clearing your cookies.

Once your cookies are cleared, restart your computer and return to the site. The login system should work for you now.