GRUB badly broken during upgrade

[Kevin O'Gorman]

I had a system with a working Ubuntu 11.04 and Xubuntu 12.04.
I went to upgrade the Ubuntu to 11.10, and all seemed well until I
went to reboot.
It got confusing after that.  It looked like all of the right kernels
were listed, but they all went to the same root.
I got in a rescue mode, and tried another update-grub.  Again it
seemed to work, but now grub goes directly to
  grub rescue>
and I have no idea what to do there.  So I'm writing this on another
system, on which I'm not likely to upgrade the Ubuntu any time soon
8o)

I have bootable CDs of all of the related versions.  I'm generally
competent at admin tasks, but only if I have a  working Linux under
me.  For this, I need help.

Thanks for any help.

-- 
Kevin O'Gorman

programmer, n. an organism that transmutes caffeine into software.