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 ('2d4a384787ad72a271f373ea77a0426f', -1, 1284079646, 1284079646, '266bbf52', 4, 0, 0)

Line : 187
File : sessions.php