[Satellite L645D, Conexant CX20585, Speaker, Internal] No sound at all

After performing a clean install of Ubuntu 11.04 on my new laptop, sound does not seem to work at all. Although it is detected and volume can be adjusted, sound cannot be heard from the laptop.

Previously running 10.10 with no sound issue.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: alsa-base 1.0.24+dfsg-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic x86_64
NonfreeKernelModules: fglrx
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
Architecture: amd64
ArecordDevices:
 **** List of CAPTURE Hardware Devices ****
 card 0: SB [HDA ATI SB], device 0: CONEXANT Analog [CONEXANT Analog]
   Subdevices: 1/1
   Subdevice #0: subdevice #0
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: supervivid 2046 F.... pulseaudio
Card0.Amixer.info:
 Card hw:0 'SB'/'HDA ATI SB at 0xf4200000 irq 16'
   Mixer name : 'Conexant CX20585'
   Components : 'HDA:14f15069,1179fdd0,00100302'
   Controls : 9
   Simple ctrls : 9
Card1.Amixer.info:
 Card hw:1 'HDMI'/'HDA ATI HDMI at 0xf4110000 irq 44'
   Mixer name : 'ATI R6xx HDMI'
   Components : 'HDA:1002aa01,00aa0100,00100100'
   Controls : 4
   Simple ctrls : 1
Card1.Amixer.values:
 Simple mixer control 'IEC958',0
   Capabilities: pswitch pswitch-joined penum
   Playback channels: Mono
   Mono: Playback [on]
Date: Tue May 10 22:01:31 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_US:en
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: alsa-driver
Symptom: audio
Symptom_AlsaPlaybackTest: ALSA playback test through plughw:SB failed
Symptom_Card: Internal Audio - HDA ATI SB
Symptom_DevicesInUse: 2046
Symptom_Jack: Speaker, Internal
Symptom_Type: No sound at all
Title: [Satellite L645D, Conexant CX20585, Speaker, Internal] No sound at all
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/18/2010
dmi.bios.vendor: Insyde Corp.
dmi.bios.version: 1.60
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: Guam
dmi.board.vendor: AMD Corp.
dmi.board.version: Base Board Version
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: Chassis Manufacturer
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnInsydeCorp.:bvr1.60:bd06/18/2010:svnTOSHIBA:pnSatelliteL645D:pvrPSK0UL-00C004:rvnAMDCorp.:rnGuam:rvrBaseBoardVersion:cvnChassisManufacturer:ct10:cvrChassisVersion:
dmi.product.name: Satellite L645D
dmi.product.version: PSK0UL-00C004
dmi.sys.vendor: TOSHIBA