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 ('c0d560855e280280542a16ec11cad969', -1, 1263433938, 1263433938, '43c372de', 0, 0, 0)

Line : 187
File : sessions.php