phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO phpbb_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('650f8975b604dbacfab043a6e19d1b9a', -1, 1369176307, 1369176307, '1716fc96', 2, 0, 0)

Line : 187
File : sessions.php