From the New York Times (h/t Boing Boing):

One of Ivanov’s losses was in a long game in a closed position (the kind where computers perform poorly), and at the end, Ivanov made a rudimentary mistake. It stood out because of how well he had played in the other games. The other loss was in the penultimate round, when the organizers, as a precaution, stopped broadcasting the games on the Internet so that people outside the playing hall could not try to assist the players.