I've created a separate thread for tracking this problem.

The attached files are from the computer at work.  I have never seen
the problem here before, only at home (both running Windows 7 64-bit).
The computer at home has been showing this symptom since later
versions of the server (1.6.x).

[118193.783] winDeinitMultiWindowWM - Noting shutdown in progress
[118193.783] winClipboardProc - winClipboardFlushWindowsMessageQueue
trapped WM_QUIT message, exiting main loop.
[118193.783] winClipboardProc - XDestroyWindow succeeded.
[118193.783] winClipboardIOErrorHandler!
[118193.783] winMultiWindowXMsgProcIOErrorHandler!
[118193.783] winInitMultiWindowXMsgProc - Caught IO Error.  Exiting.
[118193.829] winDeinitMultiWindowWM - Noting shutdown in progress
[118193.829] (II) Server terminated successfully (0). Closing log file.

Here's how I start the server:

    C:\Cygwin\bin\run.exe --quote /usr/bin/bash.exe -l -c "cd;
/usr/bin/startxwin"

Cygwin version:

    CYGWIN_NT-6.1-WOW machine 1.7.35(0.286/5/3) 2015-02-18 11:28 i686 Cygwin

I have a faint sneaking suspicion that the problem is related to
TeamViewer remote access software:

    http://www.teamviewer.com/

The reason I say this it that the only activity that would have
occurred on my home computer, during the day when I'm at the office,
would be a possible Team Viewer log-in from work.

-- 
Jim Reisert AD1C, <jjreisert@alum.mit.edu>, http://www.ad1c.us