I recently wiped my hard disk and tried to install ubuntu 12.10 but after a sucessful install from the USB,I booted from the HD and when I do I get a purple screen saying ubuntu and a loading animation but that's all it does,it keeps loading and loading an I can't get to the login screen...I'm used ext2 as the /boot and btrfs as /..I don't know if that would affect this but I did it because it kept failing to create a ext4 partition....please help!
A possible solution that strangely worked for me in the past is:
When viewing the purple ubuntu screen, wait like 1 minute then press
If you can login through the console, as Dialogos suggests, I would also plug it in to a network connection and run the updates:
As I have seen this type of behaviour before, and generally there is an update that fixes it.
Also, Ubuntu 12.10 support ends in April 2014. https://wiki.ubuntu.com/Releases