Date: 2014aug16 OS: Linux Product: Gnome Q. Gnome: Why isn't Gnome starting for me? A. They are many causes but something what worked for me once was:

dnf install gdm

This is the Gnome Display Manager. Description: GDM provides the graphical login screen, shown shortly after boot up, log out, and when user-switching. In other words, this the first thing that users see.