phpBB : Critical Error

Error creating new session

DEBUG MODE

SQL Error : 1062 Duplicate entry '-1' for key 2

INSERT INTO start_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in) VALUES ('4bdc2e7c47783775cccd12fddaedd4d9', -1, 1406086330, 1406086330, '36e343d2', 0, 0)

Line : 158
File : sessions.php