Since upgrading to Xubuntu 13.10, sound has not functioned properly (e.g. screeching when playing Skype notifications). Now, however, it does not function at all. pavucontrol only shows Dummy Output and does not recognize the built-in speakers on my Dell Precision M4600. Possibly related, the sound indicator applet does not come up when I click on it, only showing a small white bar underneath it.

I have purged and reinstalled pulseaudio. lspci -v shows:

00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 04)
    Subsystem: Dell Precision M4600
    Flags: bus master, fast devsel, latency 0, IRQ 56
    Memory at f2560000 (64-bit, non-prefetchable) [size=16K]
    Capabilities: <access denied>
    Kernel driver in use: snd_hda_intel

01:00.1 Audio device: NVIDIA Corporation GF106 High Definition Audio Controller (rev a1)
    Subsystem: Dell Device 14a3
    Flags: bus master, fast devsel, latency 0, IRQ 17
    Memory at f0080000 (32-bit, non-prefetchable) [size=16K]
    Capabilities: <access denied>
    Kernel driver in use: snd_hda_intel

The "Capabilities: <access denied>" line makes me wonder if there's a permissions issue, as the Log Out applet now shows "Restart" and "Shutdown" grayed out. groups shows me in:

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