If you want to switch to Console mode from GUI mode in GNOME follow this
simple steps
To switch to Console mode:
Press ‘Ctrl + Alt + F1′ (F2 - F6)
To switch between consoles in Console mode:
Press ‘Alt + F1′ (F2 - F6)
To switch back to GNOME GUI mode:
Press ‘Alt + F7′

refs： http://www.redhat.com/archives/redhat-install-
list/2006-August/msg00029.html