Why does my Mac decide to hang when I start winning in Chess?

I’ve been playing Chess for awhile on my MacBook Pro, always to the same effect. When I put the computer in check, it stops moving (when it’s a clear check, not checkmate.) I can’t tell if it’s thinking or what… but I let it sit for an hour, she never moved. In every game I’ve played, if I’m closing in on checkmate, and it becomes obvious, she stops moving again… Any idea why my computer feels the need to quit whenever I’m going to win? haha