phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO mex2mex_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('9b1313cc13438fecb9189c3d2e51352e', -1, 1406206745, 1406206745, '36513420', 7, 0)

Line : 170
File : sessions.php