CentOS lacking sound after yum updates

In the past week I've had a couple substantial yum updates on my CentOS
5.3 machine. Now I have no sound, and would appreciate some help with
diagnosing the problem, please. Prior to these updates the sound was
working well.

On the Gnome desktop, the sound icon is pointed to, and the tool-tip
reports "PCM: 87%". It's not muted.

System -> Administration -> Soundcard Detection brings up a window with
the first tab "Sound test", which seems a reasonable choise, and it
reports:

"The following audio device was detected.
"Vendor: Intel
"Model: Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) AC'97 Audio
Controller
"Module: snd-intel8x0"

The "Sound test" produces no audible sound and answering "No" to the
query creates an error pop-up that informs me:

"Automatic detection of the sound card did not work. This audio device
will not be available on the system. [bug-reporting suggestion]"

Other information:

$ /sbin/lsmod | grep snd
snd_intel8x0 35421 0
snd_ac97_codec 93025 1 snd_intel8x0
ac97_bus 6337 1 snd_ac97_codec
snd_seq_dummy 7877 0
snd_seq_oss 32577 0
snd_seq_midi_event 11073 1 snd_seq_oss
snd_usb_audio 77633 2
snd_seq 49585 5
snd_seq_dummy,snd_seq_oss,snd_seq_midi_event
snd_pcm_oss 42817 0
snd_usb_lib 19137 1 snd_usb_audio
snd_mixer_oss 19009 1 snd_pcm_oss
snd_rawmidi 26561 1 snd_usb_lib
snd_seq_device 11725 4
snd_seq_dummy,snd_seq_oss,snd_seq,snd_rawmidi
snd_pcm 72133 4
snd_intel8x0,snd_ac97_codec,snd_usb_audio,snd_pcm_oss
snd_hwdep 12869 1 snd_usb_audio
snd_timer 24517 2 snd_seq,snd_pcm
snd 55749 16
snd_intel8x0,snd_ac97_codec,snd_seq_oss,snd_usb_audio,snd_seq,snd_pcm_oss,snd_mixer_oss,snd_rawmidi,snd_seq_device,snd_pcm,snd_hwdep,snd_timer
soundcore 11553 1 snd
snd_page_alloc 14281 2 snd_intel8x0,snd_pcm

What can I do to get the sound operational again, please? I'm right in
the early stages of a major vhs to dvd project and desparately need the
sound to function correctly.

Thanks for your assistance.

On Tue, 03 Nov 2009 19:24:42 +0000, Greg Russell wrote:

> System -> Administration -> Soundcard Detection brings up a window with
> the first tab "Sound test", which seems a reasonable choise, and it
> reports:
>
> "The following audio device was detected. "Vendor: Intel
> "Model: Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) AC'97 Audio
> Controller
> "Module: snd-intel8x0"

The "System" tab in the application presented me with the opportunity to
"Reload audio drivers", but then informed me that a reboot was necessary,
which I performed and then the sound was working.

Apparently some updated alsa package required a module reload, but a
reboot seems a very crude way for Linux to accomplish that.

Is there some command line that would work, such as "/etc/init.d/?????
restart" or something to flush and reload a certain group of kernel
modules?