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 ('88a63db1d987e2be1c93b5e0297d6346', -1, 1265704479, 1265704479, '266bbf60', 0, 0, 0)

Line : 187
File : sessions.php