Comment 123 for bug 411574

Ok, I apologise for not reading the most recent messages here (default view only shows the first couple) but I can confirm that uninstalling sl-modem-daemon (which Ubuntu's proprietary driver utility installed for me way in the beginning) resolves the issue for me. I can now reboot and still have my sound working as it should without having to force an alsa reload.

In essence this is a bug then for sl-modem-daemon and not audio, pulseaudio, alsa, gnome, linux kernel or anything else.