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 ('9f91a35eed3d3360f6d1d7d1a0c7ed0d', -1, 1265757590, 1265757590, '266bbf6c', 1, 0, 0)

Line : 194
File : sessions.php