Comment 27 for bug 1289977

I have had the same problem. My guess is that, since I have two hard drives, the system is trying to start from the wrong drive where an old version of GRUB is installed. My solution was to start Ubuntu with a USB stick (it does not matter which version). Once you start, these commands will do it:
# mkdir /tmp/drive
# sudo mount /dev/sdX1 /tmp/drive
# sudo mount --bind /dev /tmp/drive/dev
# sudo mount --bind /proc /tmp/drive/proc
# sudo mount --bind /sys /tmp/drive/sys
# sudo chroot /tmp/drive
# dpkg-reconfigure grub-pc
Where sdX1 must be the drive where your system is installed. When you run the last command you should select the sdX drive, though I guess running it multiple times will install the new version of grub on each drive and give you some piece of mind.