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 ('965c617c1be9da72467bf7a7e39f0b93', -1, 1338162013, 1338162013, '266bb3ce', 0, 0, 0)

Line : 187
File : sessions.php