I read an article years back and I think it was in the Wall Street Journal. My understanding was that an unexpected grandmaster-level move at a point where Kasparov was expecting to see a different move occurred.

Kasparov suspected user intervention. Unfortunately the event was sponsored by IBM, so ther was potential for a conflict of interest.

He requested to see the source code and the game logs which was denied by IBM. IBM also disassembled the computer immediately after the match to re-purpose the computer for protein folding.

I think this book is rewriting history. Kasparov was devastated.

I remember that incident as well; it was the next game after the random rook move and Kasparov was already unsettled about the computer's capabilities. By my memory, it went like this:

In a complicated midgame, Kasparov moved a pawn to a square under attack. He intended to sacrifice it for positional gain, opening up his attack lines and compromising the opponent's defensive structure. Kasparov expected that a computational chess engine would seize the calculable material gain and not see the deeper positional subtleties. (Deep Blue 'only' searched ahead about 10 to 15 moves, not nearly as deep as today's computers.) Deep Blue did in fact decline the pawn sacrifice, causing Kasparov to accuse IBM of intervention, that only a human grandmaster would see the response.

This Wikipedia article mentions Kasparov setting a trap that the computer did not fall for, but it doesn't mention the details. http://en.wikipedia.org/wiki/Game_Over:_Kasparov_and_the_Mac...

It happened in game 2 of the 1997 match, the moves of which are recorded here. I haven't got the time at the moment to find the position in the game but perhaps someone can. http://en.wikipedia.org/wiki/Deep_Blue_versus_Garry_Kasparov

It was a little different from what you recall. 37. Be4 (instead of 37. Qb6) is the move that really made Garry suspect human intervention. Be4 is a much more positional move than Qb6.

Yup, there was an agreement in place that Kasparov could see the analysis that Deep Blue output. The outcome has never been decided, in my opinion, because of IBM violating the terms of the agreement.

When K requested it, he was put off. This went on, and I tracked it closely at the time, waiting for IBM to give it up. They kept saying they would, but never did to my knowledge.

Kasparov was concerned that IBM could encounter a bug, or simply a losing situation, and would have the chance to intervene with Deep Blue's calculations without anyone knowing. Deep Blue made more than one move that made Kasparov suspicious during the match. (Years later, humans interacting with computers was shown to produce much stronger results than just computers alone, even when the computers were much stronger at chess than the humans assisting them.)

Many Grandmasters have pointed out that at top-level matches, particularly world championships, psychology is the MOST important factor in deciding the outcome. This makes IBM's behavior all the worse, regardless of their reason.

(My friend Mike Valvo, now passed away, was the arbiter at the match http://www.computerhistory.org/chess/full_record.php?iid=stl... When I first met Mike, I said "There's something I always wanted to say to you!" He said "What's that?" and I said "e4" to which he responded "c5" and we proceeded to play a few moves of a Sicilian. Mike was one of a few people who had played and beaten Bobby Fischer in casual play.)

Here's an article with quotes from Kasparov that supports the thesis. The site is a classic 90's setup, and Kasparov's reaction is about halfway down the page(search for "Suicide?" without the quotes).

http://www.chessbase.com/columns/column.asp?pid=146

The block quote from the book states, "Toward the end of my interview with him, [Murray] Campbell somewhat mischievously referred to an incident that had occurred toward the end of the first game in their 1997 match with Kasparov."

This suggests rather strongly that the author of the book interviewed Campbell, rather than relying on some secondary source. Campbell, of course, may be speculating, but this seems like pretty direct attribution. The only more direct source would be Kasparov himself.

From this source which looks credible and quotes Kasparov http://www.chessbase.com/columns/column.asp?pid=146

Sitting in front of the computer Garry started trying out other lines, beginning with 44...Rf5+. Then he turned to me (his "computer expert") and said: "How could Deep Blue play 44...Rd1 and lose immediately? 44...Rf5+ also loses, but it puts up much more resistance. How can a computer commit suicide like that?" I had no immediate answer, it did indeed look very strange. Garry continued to potter around with Fritz, and suddenly he found the solution himself.

The conclusion is that it was not a bug: "It probably saw mates in 20 and more", said Garry.

Agree this all sounds apocryphal. In a losing position there were not too many choices and 44...Rd1 seems reasonable even though it may not have been the best move to prolong the game the longest.