Bug#598130: grub-installer cannot install grub-pc on amd64 ( perhaps other architecture )
I just wanted to add that the problem is not just with GRUB but with
LILO too and it is worse than that ! I tried to complete the
installation using a version of GRUB that I know that is working for
this architecture, and it was the same, so I guess it's not (or not
just) related with GRUB.