I have had problems with Grub Customizer with 12.10. One of the problems is that the up and down arrow keys don't function when I add a background image. I recently had to reinstall Ubuntu because I lost the boot capability completely with words to the effect of unable to find operating system, grub restore error and I had no luck with the grub repair tool.
After weighing the pros and cons of grub customizer I gave up using it and removed the package from my system. But boot repair tool does an excellent job in solving most booting/grub problems.