[VIA8237 - VIA 8237] ALSA test tone not correctly played back (No sound after most recent update)

I'm running Ubuntu 10.04 LTS with sound output via coax SPDiF from my motherboard. Sound worked until today when I installed what I thought was a routine update.

All volumes in alsamixer are set at max.

I would greatly appreciate any help you can offer.

Ouput of: lspci | grep audio
00:11.5 Multimedia audio controller: VIA Technologies, Inc. VT8233/A/8235/8237 AC97 Audio Controller (rev 60)

aplay -l

**** List of PLAYBACK Hardware Devices ****
card 0: V8237 [VIA 8237], device 0: VIA 8237 [VIA 8237]
  Subdevices: 4/4
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
  Subdevice #2: subdevice #2
  Subdevice #3: subdevice #3
card 0: V8237 [VIA 8237], device 1: VIA 8237 [VIA 8237]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

ProblemType: Bug
DistroRelease: Ubuntu 10.04
Package: alsa-base 1.0.22.1+dfsg-0ubuntu3
ProcVersionSignature: Ubuntu 2.6.32-23.37-generic 2.6.32.15+drm33.5
Uname: Linux 2.6.32-23-generic i686
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.21.
Architecture: i386
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: rheyns 24568 F.... pulseaudio
 /dev/snd/pcmC0D0p: rheyns 24568 F...m pulseaudio
Card0.Amixer.info:
 Card hw:0 'V8237'/'VIA 8237 with ALC655 at 0xd000, irq 22'
   Mixer name : 'Realtek ALC655 rev 0'
   Components : 'AC97a:414c4760'
   Controls : 48
   Simple ctrls : 29
Date: Fri Jul 16 18:20:17 2010
PackageArchitecture: all
ProcEnviron:
 LANG=en_US.utf8
 SHELL=/bin/bash
SelectedCard: 0 V8237 VIA8237 - VIA 8237
SourcePackage: alsa-driver
Symptom: audio
Title: [VIA8237 - VIA 8237] ALSA test tone not correctly played back
dmi.bios.date: 03/07/2006
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 080012
dmi.board.asset.tag: To Be Filled By O.E.M.
dmi.board.name: P4M800PRO-M
dmi.board.vendor: ECS
dmi.board.version: 1.0
dmi.chassis.asset.tag: 0123ABC
dmi.chassis.type: 3
dmi.chassis.vendor: ECS
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr080012:bd03/07/2006:svnECS:pnP4M800PRO-M:pvr1.0:rvnECS:rnP4M800PRO-M:rvr1.0:cvnECS:ct3:cvr1.0:
dmi.product.name: P4M800PRO-M
dmi.product.version: 1.0
dmi.sys.vendor: ECS