Latest kernel security update wont boot

[Marc Auslander <marcslists@gmail.com>]

I am running etch on a Dell with ide drives, using LILO

I just used aptitude to install the latest security update to the
2.6.18 kernel, 2.6.18.dfsg.1-13etch5

The install produced a message about the fact that it was updating the
running kernel and I should reboot right away - which I did.

Reboot failed with kernel panic which was something like:

VFS - cannot open root device "302" or block 302 not found (this is
approximate).

I tried root=/dev/hda2, and root=/dev/ide/bus0/target0/lun0/part1 -
neither worked.

I copied a backup of my old 2.6.18 kernel and initrd.img as another
kernel image and ran lilo, all from the rescue cd.

I booted the old system successfully.  I then ran a reinstall of the
kernel under aptitude, but it still won't boot.

Any suggestions?

Have my devices been somehow renumbered here? If so, how do I figure
out what the new numbering is?

Any other possibilities?