@Sebastien Bacher:
It is also happening on Unity, even if you set screen settings from AMD Catalyst (I have an AMD card), until you make changes from Gnome Control Center and save them. After that problems are "almost" fixed.
"Almost" means that before the login process everything is still messed up (my login prompt appears on my TV), but after login problem dissapear.
@Sebastien Bacher:
It is also happening on Unity, even if you set screen settings from AMD Catalyst (I have an AMD card), until you make changes from Gnome Control Center and save them. After that problems are "almost" fixed.
"Almost" means that before the login process everything is still messed up (my login prompt appears on my TV), but after login problem dissapear.