Ask to copy and paste the link below into her address bar the next time she logs onto the site, and press go, that should log her out;
http://www.babywhisperer.com/forum/login.php?logoutAfter that, get her to clear her browser cookies, that'll stop her auto login, and she can set up her own account to login then if she wants
As for the auto-login for yourself, you need to use the login boxes at the bottom of the forum, and not login at the top.
HTH, please update to let me know