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 ('f6a743a62e5085c1a78b48cb290bb2cc', -1, 1337530508, 1337530508, '266bb3ea', 0, 0, 0)

Line : 171
File : sessions.php