Yes, I already posted on this account today, sue me.

From "Deep Blue (chess computer)", Wikipedia:

In the 44th move of the first game of their second match, unknown to Kasparov, a bug in Deep Blue's code led it to enter an unintentional loop, which it exited by taking a randomly selected valid move.[23] Kasparov did not take this possibility into account, and misattributed the seemingly pointless move to "superior intelligence".[20] Subsequently, Kasparov experienced a decline in performance in the following game,[23] though he denies this was due to anxiety in the wake of Deep Blue's inscrutable move.[24]

Bolding mine.