Hello Alex!
Concerning your Synaptic problem, if you don't require the accessibility
functions, try running
gsettings set org.gnome.desktop.interface toolkit-accessibility false
This made Synaptic again work for me. Synaptic had this problem when I used a
5.5 which was upgraded from 5.0. On a new 5.5 install the problem wasn't
there, something to consider if you need accessibility.
Did you upgrade from 5.0?
Don't know what do with the sound problems, perhaps besides trying bare ALSA
without PulseAudio.
