my Desktop Environment broken - any help?

Recently, my GNOME environment was broken suddenly. Startup GNOME Shell cause segfault and die. I cannot use GDM3 at all.

henrich@hp:~ $ grep gnome-shell /var/log/syslog
Dec 15 10:51:12 hp kernel: [34944.969581] gnome-shell[10054]: segfault at 84 ip 00007f6c6186a7b9 sp 00007fff59f1dbc0 error 4 in libcogl.so.12.1.1[7f6c61821000+97000]
Dec 15 10:51:12 hp gnome-session[9565]: WARNING: Application 'gnome-shell.desktop' killed by signal 11
Dec 15 10:51:14 hp kernel: [34946.429046] gnome-shell[10202]: segfault at 84 ip 00007ffa2ae877b9 sp 00007fff2bc5c7d0 error 4 in libcogl.so.12.1.1[7ffa2ae3e000+97000]
Dec 15 10:51:14 hp gnome-session[9565]: WARNING: Application 'gnome-shell.desktop' killed by signal 11
Dec 15 10:51:14 hp gnome-session[9565]: WARNING: App 'gnome-shell.desktop' respawning too quickly

So, I've switched to KDM, and install xfce4. However, I faced to another problem - it cannot show any icons (desktop and panel).

Odd Chromium window (why red?).

Also eog says "Could not load image" "Unrecognized image file format" - Well, why? It's just a .png file. (screenshot on KDE4)

Shotwell cause segfault, too :-( (and some other GTK applications)

I cannot point out broken component. Dear lazyweb, could you tell me how to fix this situation, please?