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 ('388aa5ff41c7384d1e4881142a945d32', -1, 1406535385, 1406535385, '36e2bc8e', 7, 0)

Line : 170
File : sessions.php