I have the same problem, with the difference that the Ok button is always clickable (though nothing will happen). My root partition is formated with btrfs and I tried to install grub to /dev/sda9 (I have no lvm on my hard drive). As far as I can tell the error causing the bootloader install to fail is Bug #703009.
** Attachment added: "Screenshot" https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/686859/+attachment/1983979/+files/InstallScreenShot -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/686859 Title: "Bootloader install failed" cannot be closed -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
