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 ('7582000ce8e9e8b6cd77a424b27f2e09', -1, 1268337481, 1268337481, '266bbf58', 31, 0, 0)

Line : 187
File : sessions.php