After upgrading my Ubuntu server from 10.10 to 11.04 using the “do-release-upgrade” method, my system would no longer boot.
It was stuck on a GRUB shell. I downloaded the liveCD, booted from that and ran the excellent Boot-Repair utility. I had to install it using apt-get, so you need an internet connection. They should include it in the liveCD. I belive you can also download a Boot-Repair ISO file to boot from.
But the Boot-Repair tool worked great and fixed my GRUB in no time.
I see a lot of problems with GRUB after the upgrade. Maybe it’s a bug that affects people who, in the past, already upgraded from 9.x or 8.x to 10.x. So people who had GRUB v1 at some point in time.