"modprobe snd" fails for missing symbols in hardy

[Alex Rolfe]

Binary package hint: linux-ubuntu-modules-2.6.24-12-generic

In the past few days, sound starting failing on my T60 with Intel HDA sound. The cause seems to be that the relevant modules can't be loaded, eg:
 root@register-machine:/etc/modprobe.d# modprobe snd
FATAL: Error inserting snd (/lib/modules/2.6.24-12-generic/ubuntu/sound/alsa-driver/acore/snd.ko): Unknown symbol in module, or unknown parameter (see dmesg)
FATAL: Error running install command for snd

and dmesg reports:
[ 1686.167423] snd: Unknown symbol unregister_sound_special
[ 1686.167559] snd: Unknown symbol register_sound_special_device
[ 1686.167944] snd: Unknown symbol sound_class

There are lots of other missing symbols if I try to "modprobe snd_hda_intel"; the output from dmesg is in the attached file along with the other information for debugging sound problems. I have not made any changes or updates to the modules.
Kernel is 2.6.24-12-generic, package version 2.6.24-12.19. linux-ubuntu-modules-2.6.24-12-generic is version 2.6.24-12.16.