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 ('b5f5d6bb7e6a23bf831edd3be77371fc', -1, 1263413914, 1263413914, '43c372de', 8, 0, 0)

Line : 187
File : sessions.php