It looks like some gnome configuration problem. Please enable Xvfb script again, edit it to start gnome-session without involving Xsession script . To do that change last line your script to: DISPLAY=:0 nohup /usr/bin/gnome-session &
(make sure that gnome-session path is correct, you can verify it with command whereis gnome-session
). Then reboot system and try again to connect.
If that doesn’t help. You need to check system logs to find the reason why gnome-session couldn’t start. You could consider also to reinstall GUI environment.