This is probably because you have not carried out one of the CFX-4.4 installation steps to set the software mount points. Two mount points need to set, one for /tmp and one for /bin. Select the option Tools > Reset Mount Table on the CFX-4 Launcher. Try CFX-Build again; it should now work. If it still does not work select the option Tools > Command Line from the CFX-4 Launcher to open up a bash window. This may produce an error message that the /tmp directory cannot be found. Ignore this and continue. Type the command mount in the bash window. Check to see what /tmp and /bin are set to – the vaulues in the first column of the output from mount show what they have been set to. Check what /tmp is set to. If it is set to c:temp, make sure that this directory exists on your hard disk; if it does not, create it and then make sure that the TMP user variable was set to c:temp using Control Panel > System > Advanced > User Variables. Check what /bin is set to. It should be set the installation directory that you specified when you installed the Cygwin software from the installation CD. The default is c:cygnus. If /bin is set incorrectly type umount /bin mount ‘c:cygnuscygwin-b20H-i586-cygwin32bin’ /bin taking care to put the correct directory name in the second line. Now exit the bash window, ignoring any error messages that may appear. Try CFX-Build again. This time it should work fine.