grub install fails

I created an install disk based on a Linux Mint 18 distro with pinguy. The install works fine until the bootloader (grub) has to be written to the selected location. A dialog opens saying that grub can't be written to the location selected an I am asked to select another location. Since there is only one drive available, there is no other location.
When I install from the original Linux Mint 18 CD everything works fine. How can I diagnose and possibly fix this?