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) VALUES ('b18858c0e16f80d8070540b9db11b57f', -1, 1406232102, 1406232102, '36e0d66d', 33, 0)

Line : 315
File : sessions.php