Afaik, I thought the engineers running the machine were reprogramming during the game to handle changes in Kasparov's technique. Please someone with more knowledge chime in, but from my memory it was more like he was competing against computationally augmented human opponent. He wasn't beaten by a computer, he was beaten by a team of engineers using a computer.
some corroboration on http://en.wikipedia.org/wiki/Deep_Blue_(chess_computer)