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 ('46e734493dcd04ca932d82d3b75ccc73', -1, 1369160815, 1369160815, '6b169ccd', 3, 0, 0)

Line : 187
File : sessions.php