Are you getting any artifacts on the screen when it fails to load the GUI and defualt to CLI?

Also becuase of the random events it is time for you to review the xorg log that adam recommended, in that file you should be find error message that we can help you to translate into remedial actions.

Then I believe the issue may be with the gnome utilities, I would recommend reinstalling gnome and gdm, rather than forcing yourself to adapt to a new desktop environment.