diff -urw xc-orig/programs/Xserver/hw/xwin/InitOutput.c xc/programs/Xserver/hw/xwin/InitOutput.c
--- xc-orig/programs/Xserver/hw/xwin/InitOutput.c	2010-02-26 01:08:16.471542311 +0100
+++ xc/programs/Xserver/hw/xwin/InitOutput.c	2010-02-26 01:25:24.370543791 +0100
@@ -1180,8 +1180,10 @@
 winCheckDisplayNumber ()
 {
   int			nDisp;
+  int           i;
   HANDLE		mutex;
   char			name[MAX_PATH];
+  char *        fs = "";
   char *		pszPrefix = '\0';
   OSVERSIONINFO		osvi = {0};
 
@@ -1207,8 +1209,13 @@
       pszPrefix = "Global\\";
     }
 
+  for (i = 0; i < g_iNumScreens; ++i)
+      if (g_ScreenInfo[i].fFullScreen) {
+          fs = "FS";
+          break;
+      }
   /* Setup Cygwin/X specific part of name */
-  snprintf (name, sizeof(name), "%sCYGWINX_DISPLAY:%d", pszPrefix, nDisp);
+  snprintf (name, sizeof(name), "%sXMING_DISPLAY%s:%d", pszPrefix, fs, nDisp);
 
   /* Windows automatically releases the mutex when this process exits */
   mutex = CreateMutex (NULL, FALSE, name);