As mentioned, this is an ALSA bug. ALSA is lying to us. Reassigning.

Please add some info about the sound driver used here. Thanks.

http://www.smolts.org/client/show/pub_d16f8da2-4e5e-4c8f-81f3-7d7a7a4a2db3

I'm seeing this too:

# lspci|grep -i audio; uname -a; rpm -q pulseaudio

00:0c.1 Multimedia controller: Brooktree Corporation Bt878 Audio Capture (rev 11)
00:11.5 Multimedia audio controller: VIA Technologies, Inc. VT8233/A/8235/8237 AC97 Audio Controller (rev 60)
Linux mmouse.moneta.optonline.net 2.6.27.9-159.fc10.i686 #1 SMP Tue Dec 16 15:12:04 EST 2008 i686 athlon i386 GNU/Linux
pulseaudio-0.9.13-6.fc10.i386

/var/log/messages (while playing audio in rhythmbox):

Jan 11 21:29:13 mmouse pulseaudio[30756]: module-alsa-sink.c: ALSA woke us up to
 write new data to the device, but there was actually nothing to write! Most lik
ely this is an ALSA driver bug. Please report this issue to the PulseAudio devel
opers.
Jan 11 21:29:31 mmouse pulseaudio[30756]: module-alsa-sink.c: ALSA woke us up to
 write new data to the device, but there was actually nothing to write! Most lik
ely this is an ALSA driver bug. Please report this issue to the PulseAudio devel
opers.
Jan 11 21:29:31 mmouse pulseaudio[30756]: module-alsa-sink.c: ALSA woke us up to
 write new data to the device, but there was actually nothing to write! Most lik
ely this is an ALSA driver bug. Please report this issue to the PulseAudio devel
opers.
Jan 11 21:29:31 mmouse pulseaudio[30756]: module-alsa-sink.c: ALSA woke us up to
 write new data to the device, but there was actually nothing to write! Most lik
ely this is an ALSA driver bug. Please report this issue to the PulseAudio devel
opers.
...

I have the same problem.

I use 2 sound cards. 
1. "ESS Technology ES1988 Allegro-1 ESS Allegro-1 Audiodrive" works perfectly 
2. "VIA Technologies, Inc. VT8233/A/8235/8237 AC97 Audio Controller" doesn't work.

when i try to use VIA AC97 card i get this in /var/log/messages:

Jan 27 21:18:02 dream pulseaudio[2667]: module-alsa-sink.c: ALSA woke us up to write new data to the device, but therewas actually nothing to write! Most likely this is an ALSA driver bug. Please report this issue to the PulseAudio developers.

moreover when i try to use ESS card via pulseaudio i get intermittent sounds :(

Hardware:
http://www.smolts.org/client/show/pub_4cf67e4c-0fd4-473f-8df2-177fd0b736cf

alsa 1.0.17
kernel-2.6.27.12-170.2.5.fc10.i686
pulseaudio-0.9.13-6.fc10.i386

----/proc/asound/cards:
 0 [PCI            ]: Allegro - ESS Allegro PCI
                      ESS Allegro PCI at 0xe800, irq 19
 1 [V8235          ]: VIA8233 - VIA 8235
                      VIA 8235 with ALC650F at 0xd800, irq 22
----/proc/asound/modules
 0 snd_maestro3
 1 snd_via82xx

I am getting the same comment also:
_______________
pulseaudio[3024]: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is an ALSA driver bug. Please report this issue to the PulseAudio developers.
_______________
Details:

alsa 1.0.19
pulseaudion 0.9.12-6
kernel 2.6.27.12-170.2.5.fc10.i686 #1 SMP

Device:
00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 03)
01:00.1 Audio device: ATI Technologies Inc RV620 Audio device [Radeon HD 34xx Series]

 0 [Intel          ]: HDA-Intel - HDA Intel
                      HDA Intel at 0xd5200000 irq 22
 1 [HDMI           ]: HDA-Intel - HDA ATI HDMI
                      HDA ATI HDMI at 0xd0030000 irq 17

_______________

Let me know if you need more details.

Partha

See bug 471941, comment 8 for a workaround for your message log filling up.

I am seeing this also with my ESS Maestro3.

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