A cold, calculating computer called "X3D Fritz" swiftly took advantage of an all-too-human error by world No. 1 chess player Garry Kasparov on Thursday to win the second game of their four-game match in New York.

A tense, evenly balanced struggle became a mismatch on Kasparov's 32nd turn when the grandmaster blundered with a rook move that allowed the computer to penetrate his defenses with an unstoppable attack -- a queen, a rook and a pawn marching down the board on its way to converting into another queen.

"I just blundered," Kasparov, 40, who had far less time left than the computer, told reporters.

Kasparov, who played with the black pieces, resigned after white's 39th move and three hours and 40 minutes play. His mistake was reminiscent of one he committed on Jan. 30 in the third game of his six-game match against Israeli-built world chess computer champion Deep Junior. That was also an error with a rook on the 32nd move.

The match ended in a 3-3 tie. In chess matches, one point is awarded for a win and a 1/2 point for a draw.

X3D Fritz, a combination of German-built Fritz software and New York-based X3D Technologies' virtual reality software, plays as well as a solid grandmaster, according to chess experts. It leads Kasparov by 1-1/2 points to a 1/2.

"Your brain sort of turns off in these situations and it was just a case of Garry made a mistake and it was a flaw the computer saw immediately," said John Fernandez, chess consultant with X3D Technologies.

The first game on Tuesday was drawn. The third is scheduled for Sunday and the final game is on Tuesday in the match in which the winner stands to collect $250,000.

In a departure from tournament chess and other so-called man vs machine matches, Azerbaijan-born Kasparov is playing the program without physically moving pieces on a board.

Instead, he sits in front of a computer monitor wearing 3-D glasses that make the on-screen image of the board appear to float in front of him. He announces his moves on a voice-recognition system and a human operator makes sure his silicon opponent records them correctly.

Kasparov lost his world championship title to Vladimir Kramnik of Russia in 2000, but he is still ranked No. 1 by the International Chess Federation.