I am by no means an expert at this but as a fellow head scratcher in a simular situation. I might be able to help.
I had that problem, because of my network connection.
From the console, try to ping your router to confirm connectivity to it (assuming your web connection is through a router).
ping 10.1.1.1 (or whatever address you have to ping to)
Then if that is okay check that DNS is working.
If not, check interfaces file as below.
My problem was that I had only one NIC, and the settings in /etc/network/interfaces was incorrect.
I edited the file so that I was using DHCP (router provided address and DNS)auto eth0
eth0 inet dhcp
Saved it then,sudo ifdown eth0
(may not be needed)sudo ifup eth0
Then it was a goer.
I got the failed to Setup X too, but I think I checked the other screens (Ctrl + ALT + F1 through F?) and found that there were things still going on.
I have learnt that if the PC seems to have hung, I wait, go make a coffee, check if anything is going on in the other screens.
Then but only then do I reluctently reboot.
Hope this helps
Let me know how you go.