"Grub-efi package failed to install to /target/" on Kubuntu 12.10

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http://askubuntu.com – I tried to install Kubuntu 12.10 (AMD64+mac) to my Mac Mini via a live USB. The live USB boots OK (with the help of rEFIt), but during install I get the error "grub-efi package failed to install to /target/." Then when trying to boot from that partition, I get a grub error about an unrecognized filesystem, and it drops down to grub rescue. Any ideas? (HowTos)