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 ('23ff30aa79926fb1d2e382e4b2b737f9', -1, 1369469857, 1369469857, '36ea4337', -1, 0, 0)

Line : 187
File : sessions.php