sound works randomly?

[Tom Horsley]

Almost as mysteriously as sound stopped working, it
has now started working again. The default pulseaudio
output has always been set to HDMI, but my motherboard
does look like two separate audio devices to linux,
so there were two "profiles".

Apparently some randomly selected collection of apps
started being directed to the 2nd profile, because when
I plugged in some earphones, sound came out of them
when running the apparently silent apps.

I've set the 2nd profile to "off" rather than "headphones"
and finally everyone seems to be using the same HDMI
default output they should have been using all along.

The weird thing is that as part of my experiments,
I created a brand new user and logged in with
different kinds of sessions (GNOME 3, KDE, FVWM)
and the collection of seemingly silent apps
was different in each session.