I switched to the freshly-published Mint 17 Cinnamon release ISO and had the same problem. Then I switched from using UNetbootin (OSX) to using the Ubuntu instructions for making a bootable USB drive natively in OSX (http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-mac-osx). That method created a bootable flash drive whose installer completed successfully.
I switched to the freshly-published Mint 17 Cinnamon release ISO and had the same problem. Then I switched from using UNetbootin (OSX) to using the Ubuntu instructions for making a bootable USB drive natively in OSX (http:// www.ubuntu. com/download/ desktop/ create- a-usb-stick- on-mac- osx). That method created a bootable flash drive whose installer completed successfully.