It should not be like that. What version of moodle you are at it. The beta 2.0 does not work with this. Just clear all your browser cache, temp files etc and start browser with clean slate. Otherwise, change the session handling to database and it should be then fine. with regards
Try to clear all entries in /home/moodledata/sessions folder and try to relogin. If you are using database to handle sessions, clear all entries in database table mdl_sessions2. This should solve the problem with regards