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 ('e56f5bb196b77bf68f56bb0f6cff949e', -1, 1406298832, 1406298832, '36e250c4', -1, 0, 0)

Line : 188
File : sessions.php