I had my winders partition on my laptop go tits up on my, so I had to reinstall it. Now, that, of course, wiped out the grubster. My windows partition is sda1, swap is sda2, root is sda5, /boot is sda6, with var, opt, and home partitions as well. The mtab in /etc is good, but what's the magic incantation when booted from a ubuntu live disc to get grub in and reading /boot/menu.lst etc correctly? I've installed grub (using grub-install --root-directory=/mnt) and now when it boots I get a grub prompt, but I have no idea how to make it continue on its merry way....

It turned out that I needed to get the 9.04 ubuntu install image, not the 9.10... it's a known problem that this happens when you use the 9.10 install cd to put it on a system installed from an earlier version. I downloaded and burned the 9.04 install, and basically did the exact same thing and it came right up.

Seems kind of dumb... I actually used the 9.10 install cd because I'd done the dist-upgrade to 9.10 several weeks back, but it turns out that's a no-no.