User attempts to start GNOME fail with error "Failed to connect to socket /tmp/dbus-[random]: Connection refused"

Issue

• One of our users is trying to run the GUI, but when switching to the graphical desktop, it doesn't start.
• When we try to use the VNC viewer connecting to the tigervnc server on this machine, the viewer is getting logged in, but the display is black.

• When trying to run VNC, we're seeing these errors in our VNC log:

  gnome-session: WARNING: Could not make bus activated clients aware of DISPLAY=:1 environment variable: Failed to connect to socket /tmp/dbus-ohmajuPoo7: Connection refused
  gnome-session: WARNING: Could not make bus activated clients aware of GNOME_DESKTOP_SESSION_ID=this-is-deprecated environment variable: Failed to connect to socket /tmp/dbus-ohmajuPoo7: Connection refused
  gnome-session: WARNING: Could not make bus activated clients aware of SESSION_MANAGER=local/unix:@/tmp/.ICE-unix/0000,unix/unix:/tmp/.ICE-unix/0000 environment variable: Failed to connect to socket /tmp/dbus-ohmajuPoo7: Connection refused