Had the same problem, if you didn't fix it yet here is what I did:
First, verify /etc/apt/sources.list. Could use apt-spy / netselect-apt to know fastest apt mirror
apt-get install install x-window-system
Once X installed proceed with gnome, following packages are minimum but gives you gnome gui based interface... so on it's easier to add other packages from synaptic.
apt-get install gnome-core gdm synaptic