I tried to upgrade from 11.10 to 12.04lts via a usb. I went to "Try Ubuntu" first and it loaded fine. Then I clicked the Install icon on the desktop. Then I selected Upgrade. It asked a few questions then asked for my user name and machine name. I thought why does it need to know my machine name if I am upgrading. So I tried to back out. There was no quit button. So I kept hitting back. Then finally I just clicked shutdown.

When I try to boot I get:
BusyBox b1.18.4 (Ubuntu 1:1.18.4-2ubuntu2) built-in shell (ash)
Enter 'help' for a list of built-in commands.