This issue can be caused by corrupted cookies. * "Clear the Cache": Firefox > Preferences > Advanced > Network > Offline Storage (Cache): "Clear Now" * "Remove the Cookies" from sites causing problems: Firefox > Preferences > Privacy > Cookies: "Show Cookies" ---- If clearing the cookies doesn't help then it is possible that the file <i>cookies.sqlite</i> that stores the cookies is corrupted. Rename (or delete) <b>cookies.sqlite</b> (cookies.sqlite.old) and delete <b>cookies.sqlite-journal</b> and <b>cookies.txt</b>, if they exist, in the [http://kb.mozillazine.org/Profile_folder_-_Firefox Profile Folder] in case the file cookies.sqlite got corrupted. * http://kb.mozillazine.org/Cookies#Removing_cookies