Cygwin: Can't quit Emacs using C-x C-c
On some installations of Cygwin on Windows XP, it is impossible to exit Emacs using C-x C-x. After digging around in the message lists, I found out that the C-x key is trapped by the OS. The fix for this is to set a Windows environment variable:
CYGWIN=tty
Then quit all of the Cygwin windows and start them up again. This worked for me.