F16 kernel panic! Unable to select previous OS from Grub List.

[nicksfx]

On latest kernel update (via automatic software update), Fedora 15 is not able to boot.
"Kernel panic: - not syncing: VFS ...." Error.

While booting Grub shows OS list but goes straightaway to the first Kernel selection, that doesn't work. (I am unable to move arrow down to select previous version).

Is there a way I can boot up and change grub.conf file?

[goodfella]

Boot off the iso DVD and enter repair mode.

[nicksfx]

Will the repair work if my original install was LUKS encrypted?