On Sunday 30 April 2017 16.36:34 dave wrote:
> after dumping about 4 minutes of TOP to a file I found the culprit.
> Nautilus causes this background change. now the question  How did this
> app start in the first place?

What is your default Desktop manager? Nautilus being the default file manager 
for gdm, I could imagine a link.

I've seen Gnome 3 bloquing TDE in some distributions. Maybe there is something 
like that with Ubuntu? As I don't run Ubuntu and don't have nautilus 
installed I never saw this behaviour.

Thierry