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 ('41dc2a3944ab4a2371eb31c397e0bf3c', -1, 1284062926, 1284062926, '266bbf54', 1, 0, 0)

Line : 187
File : sessions.php