I downloaded the installation image, right to the flash drive, then boot from it.
I choose Install Ubuntu, and in the next window, described three recommended conditions, the last-established connection to the Internet.
So, I close with this condition the red X, that is, installer does not see a network.
But if I choose Try Ubuntu, the connection is established and Firefox opens the page.
I am connecting to the Internet via a network card.
What is the problem, and how can I get the installation to connect to the Internet?
P.S. distribution - ubuntu 12.04 (also tried kubuntu 12.04, ubuntu 12.10 beta1 - the result is the same)