There was a posting earlier this week about XWin -multiwindow hanging intermittently. This has been happening to me as well. It almost always hangs.
One suggestion made in a followup post was to "mount -b c:/cygwin/tmp /tmp". This didn't work for me. Here's the output from /tmp/XWin.log Welcome to the XWin X Server Vendor: The Cygwin/X Project Release: 6.7.0.0-9 Contact: [EMAIL PROTECTED] XWin was started with the following command line: XWin -multiwindow ddxProcessArgument - Initializing default screens winInitializeDefaultScreens - w 2560 h 1024 winInitializeDefaultScreens - Returning _XSERVTransmkdir: Owner of /tmp/.X11-unix should be set to root winValidateArgs - g_iNumScreens: 1 iMaxConsecutiveScreen: 1 (II) XF86Config is not supported (II) See http://x.cygwin.com/docs/faq/cygwin-x-faq.html for more information winDetectSupportedEngines - Windows NT/2000/XP winDetectSupportedEngines - DirectDraw installed winDetectSupportedEngines - DirectDraw4 installed winDetectSupportedEngines - Returning, supported engines 00000007 winSetEngine - Multi Window or Rootless => ShadowGDI winAdjustVideoModeShadowGDI - Using Windows display depth of 32 bits per pixel winAllocateFBShadowGDI - Creating DIB with width: 2365 height: 996 depth: 32 winFinishScreenInitFB - Masks: 00ff0000 0000ff00 000000ff winInitVisualsShadowGDI - Masks 00ff0000 0000ff00 000000ff BPRGB 8 d 24 bpp 32 null screen fn ReparentWindow null screen fn RestackWindow InitQueue - Calling pthread_mutex_init InitQueue - pthread_mutex_init returned InitQueue - Calling pthread_cond_init InitQueue - pthread_cond_init returned winInitMultiWindowWM - Hello winInitMultiWindowWM - Calling pthread_mutex_lock () winMultiWindowXMsgProc - Hello winMultiWindowXMsgProc - Calling pthread_mutex_lock () MIT-SHM extension disabled due to lack of kernel support XFree86-Bigfont extension local-client optimization disabled due to lack of shared memory support in the kernel (--) Setting autorepeat to delay=500, rate=31 (--) winConfigKeyboard - Layout: "00000409" (00000409) (EE) Keyboardlayout "US" (00000409) is unknown Rules = "xorg" Model = "pc101" Layout = "us" Variant = "(null)" Options = "(null)" Could not init font path element /usr/X11R6/lib/X11/fonts/CID/, removing from list! winPointerWarpCursor - Discarding first warp: 1182 498 winInitMultiWindowWM - pthread_mutex_lock () returned. winMultiWindowXMsgProc - pthread_mutex_lock () returned. winMultiWindowXMsgProc - pthread_mutex_unlock () returned. winMultiWindowXMsgProc - DISPLAY=127.0.0.1:0.0 winInitMultiWindowWM - pthread_mutex_unlock () returned. winInitMultiWindowWM - DISPLAY=127.0.0.1:0.0 winProcEstablishConnection - Hello winProcEstablishConnection - Clipboard is not enabled, returning. winMultiWindowXMsgProc - XOpenDisplay () returned and successfully opened the display. winInitMultiWindowWM - XOpenDisplay () returned and successfully opened the display.