In my case the network connection was from a usb connected 3g dongle,
the Huawei E220 so the network hardware itself should not be directly
connected to the sound hw.
Adding the ifconfig ppp0 ( if i remember correctly ) down in the alsa
shutdown script fixed the problem.
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storing mixer
The fix with shuting down the network interface is confirmed. I
experience the same problem with haning on alsa shutdown on a hp laptop
with a usb 3g modem. But if i disconnect it using the network manager
menu option ( below the list of available networks when left clicking on
the network manager
