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 ('ff4a58f604e93ec8f40a9c81c0e81728', -1, 1369140822, 1369140822, '1714c4b3', -1, 0, 0)

Line : 187
File : sessions.php