phpBB : Critical Error

Error creating new session

DEBUG MODE

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

INSERT INTO phpbb2_sessions (session_id, session_user_id, session_start, session_time, session_ip, session_page, session_logged_in, session_admin) VALUES ('65e536baa5e3456bf7f8dcaad5ae4025', -1, 1268626727, 1268626727, '266bbf56', 13, 0, 0)

Line : 187
File : sessions.php