Comment 2 for bug 533716

The contents of the /boot partition:

ubuntu@ubuntu:/mnt/grub$ ls -al
total 6
drwxr-xr-x 2 root root 1024 2010-03-07 19:48 .
drwxr-xr-x 4 root root 1024 2010-03-07 10:40 ..
-rw-r--r-- 1 root root 30 2010-03-07 10:40 device.map
-r--r--r-- 1 root root 2496 2010-03-07 19:48 grub.cfg

shows that a lot of files used by grub are missing, in particular core.img.
Therefore it seems that the source of the problem is the installer which failed to copy them.