This article is from the GNU Chess and XBoard FAQ, by Tim Mann firstname.lastname@example.org with numerous contributions by others.
If you are using Crafty, be certain to get the version compiled for
Win32 (wcrafty.exe), not the version compiled for MS-DOS (crafty.exe).
Also, be sure you have the current version of WinBoard. WinBoard 3.4.1
and earlier had a bug that caused this problem to occur with all chess
This problem is reported to still happen occasionally, for unknown
reasons. You can generally stop the rogue Crafty by pressing
Ctrl+Alt+Del, selecting the Crafty process from the menu, and pressing
the End Task button.