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 ('9e3c9be890a0d5aff20770b49c1f7c71', -1, 1368984193, 1368984193, '36ea4337', 3, 0, 0)

Line : 187
File : sessions.php