[SOLVED] cannot configure or access sound card

[terence]

Hello,

I have a Acer Aspire 5810T laptop running 64-bit CentOS 6.5. Until a while ago, the sound was working perfectly. But now, all of a sudden, every time I use any sound related application (audacity, xmms, alsamixer, aplay etc), I keep getting the error message "PulseAudio: Unable to connect: Connection refused", and I get no sound. As far as I'm aware, I haven't messed around with the sound set up at all in the meantime. The output of lspci is as follows:

00:00.0 Host bridge: Intel Corporation Mobile 4 Series Chipset Memory Controller Hub (rev 07)
00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)
00:02.1 Display controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)
00:1a.0 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #4 (rev 03)
00:1a.1 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #5 (rev 03)
00:1a.7 USB controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #2 (rev 03)
00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 03)
00:1c.0 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 1 (rev 03)
00:1c.1 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 2 (rev 03)
00:1d.0 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #1 (rev 03)
00:1d.1 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #2 (rev 03)
00:1d.2 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #3 (rev 03)
00:1d.3 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #6 (rev 03)
00:1d.7 USB controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #1 (rev 03)
00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev 93)
00:1f.0 ISA bridge: Intel Corporation ICH9M-E LPC Interface Controller (rev 03)
00:1f.2 SATA controller: Intel Corporation 82801IBM/IEM (ICH9M/ICH9M-E) 4 port SATA Controller [AHCI mode] (rev 03)
00:1f.3 SMBus: Intel Corporation 82801I (ICH9 Family) SMBus Controller (rev 03)
00:1f.6 Signal processing controller: Intel Corporation 82801I (ICH9 Family) Thermal Subsystem (rev 03)
01:00.0 Ethernet controller: Qualcomm Atheros AR8131 Gigabit Ethernet (rev c0)
02:00.0 Network controller: Intel Corporation WiFi Link 5100

The output of lsmod | grep snd is as follows:

snd_hda_codec_hdmi 41160 1
snd_hda_codec_realtek 52207 1
snd_hda_intel 43912 0
snd_hda_codec 192975 3 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel
snd_hwdep 13652 1 snd_hda_codec
snd_seq 61602 0
snd_seq_device 14490 1 snd_seq
snd_pcm 92957 3 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec
snd_timer 29718 2 snd_seq,snd_pcm
snd 79282 9 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_seq,snd_seq_device,snd_pcm,snd_timer
soundcore 14996 1 snd
snd_page_alloc 18798 2 snd_hda_intel,snd_pcm

In the gnome desktop, if I go to System>Preferences>Sound, all I get is a window saying "Waiting for sound
system to respond", and nothing happens, so I can't even try to (re-)configure the sound card. The output of
aplay -L is as follows:

default
Default
front:CARD=Intel,DEV=0
HDA Intel, ALC269 Analog
Front speakers
surround40:CARD=Intel,DEV=0
HDA Intel, ALC269 Analog
4.0 Surround output to Front and Rear speakers
surround41:CARD=Intel,DEV=0
HDA Intel, ALC269 Analog
4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=Intel,DEV=0
HDA Intel, ALC269 Analog
5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=Intel,DEV=0
HDA Intel, ALC269 Analog
5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=Intel,DEV=0
HDA Intel, ALC269 Analog
7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=Intel,DEV=0
HDA Intel, ALC269 Digital
IEC958 (S/PDIF) Digital Audio Output
hdmi:CARD=Intel,DEV=0
HDA Intel, HDMI 0
HDMI Audio Output

I did a bit more digging and looked in /var/log/messages, and I see a lot messages as follows relating to
pulseaudio:

Apr 11 20:11:29 localhost pulseaudio[4026]: module-console-kit.c: GetSessionsForUnixUser() call failed: org.freedesktop.DBus.Error.Spawn.ExecFailed: Failed to execute program /lib64/dbus-1/dbus-daemon-launch-helper: Success
Apr 11 20:11:29 localhost pulseaudio[4026]: module.c: Failed to load module "module-console-kit" (argument: ""): initialization failed.
Apr 11 20:11:29 localhost pulseaudio[4026]: main.c: Module load failed.
Apr 11 20:11:29 localhost pulseaudio[4026]: main.c: Failed to initialize daemon.
Apr 11 20:11:29 localhost pulseaudio[4024]: main.c: Daemon startup failed.

And sure enough, there is no pulseaudio process running in the background.

I have a desktop PC with exactly the same set up (though with different sound hardware), and sound works perfectly on that machine. The only thing I can think of that might have messed up the sound on the laptop
is that I just installed Skype on it, although all I did was to sign up for a Skype account and logged into it from
skype - I haven't actually used it to contact anyone yet.

I tried all the suggested solutions I've found so far to similar problems: deleting ~/.pulse*, reinstalling pulseaudio - none of it worked. Could anyone please suggest anything else I could try to fix this problem?
Thanks in advance for any help,
Terence

[terence]

I've finally managed to resolve this. As I said, I tried reinstalling pulseaudio and also alsa, without success.
But one of the pulseaudio error messages in /var/log/messages relates to dbus, so on the off chance I reinstalled all the dbus packages using 'yum reinstall \*dbus\*' and sound worked again afterwards!

I still have no idea how the dbus installation got messed up. As far as I can remember, I never ran any sound
applications that uses pulseaudio/alsa as root. So I have one remaining question: is there anything else which
normally needs to be done as root which might have messed up the dbus set-up, and which I should be careful
about in future? I don't think the problem was with the personal ~/.dbus directory - I couldn't get the sound to work as root or any other user.