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 ('4f5bf24b4858b15540c1bfe3a6b4c5b0', -1, 1329162649, 1329162649, '266bb3f3', 0, 0, 0)

Line : 189
File : sessions.php