<--snip-->
>
> Hardware:
>
> 1. Netbook, CPU: Intel Atom N2600, GPU: Integrated controller, RAM: 2GB.
> In this netbook the problem leave to appear afterwards to edit the GRUB
> to turn off the load of AppArmor, with apparmor=0.
> 2. Desktop PC, CPU: AMD Athlon 64 3000+, GPU: NVIDIA GeForce4 MX 440,
> RAM: 3GB.
> In this PC the problem did not disappear deactivating AppArmor.
>
> Possibilities:
> - Too old hardware?
> - AppArmor?
> - XFCE, now 100% with GTK3?
The nouveau driver is notably buggy on 'old' hardware, twenty year old graphics hardware is positively antique.
Nvidia hardware past five years old should be considered 'Legacy' and only legacy OS's should be expected to function, certainly not modern compositors.