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 ('c12f66a92cfe55e2c3e115d9f7d519c6', -1, 1283902297, 1283902297, '266bbf6c', -10, 0, 0)

Line : 187
File : sessions.php