Unclickable squares?

[edgeman16]

As you can see at about 1:35 into this video: http://youtu.be/R7-NWBK8Ey8?t=1m22s There is a square that MSolver tries to click on that Minesweeper refuses to clear...

Not sure what's happening there...

You will see the mouse moving erratically afterwards and then the game ends when I manage to manually click on some other square...