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) VALUES ('fea6ee64e8c4bb492b7e1afae0d4a9fa', -1, 1406806002, 1406806002, '36c4b56d', -8, 0)

Line : 158
File : /home/popthet/public_html/forum/includes/sessions.php