Comment 50 for bug 360378

I just encountered this performing 'aptitude safe-upgrade' from 2.6.32-22.36 to 2.6.32-24.43 (generic)
Had two similar machines upgrade fine.
The previous 2.6.32-22.36 grub (v0.97) menu entry continued to boot fine.
After reading these comments I tried, after booting the previous kernel:

update-initramfs -k 2.6.32-24-generic -d
update-initramfs -k 2.6.32-24-generic -c

(substitute your own offending version) to remove and recreate the initramfs for the new kernel.
It booted OK. Have only booted once. No idea how permanent this is.