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 ('d5597d02b7aa0e88a8d43bfcc4a68b2a', -1, 1369203088, 1369203088, '32116df8', -1, 0, 0)

Line : 187
File : sessions.php