Comment 6 for bug 290140

I just had this very same issue after installing Jaunty from the alternate disk and afterwards switching to grub (I hate LILO).

I just today found that there were these two lines missing in the file /etc/kernel-img.conf:

postinst_hook = update-grub
postrm_hook = update-grub

I have no idea where those lines should have come from, but after inserting them into that file the update-grub skript was called. Could this be your Problem?