re :''I want to work offline,'' Are you starting up Thunderbird already in offline mode? Are you starting up as normal, but then selecting to work offline? Do you have any imap mail accounts? re :'' popup window keeps prompting me to sign in with my '''master password.''''' 'Have you setup to use a 'Master Password' ? This is not the same password as used to sign in to mail accounts. info on master password: http://kb.mozillazine.org/Master_password