Did you check keyboard settings when you boot in live mode?
Yes! I did it. Twice. I'm 2-years experience linux user. I'm always pay attention on this.
Logging form have behaviour like it recognize pass, but then loading again form login/pass without any alerts about wrong pass or login. I try login in the guest mode and try change user with "su" in console. But I couldn't do this.
I switched in console mode with ctrl+alt+f1. And I DID IT!! My pass is right. Problem with login form(I don't know name of this programm). Have you any ideas, how I can fix it?
upd_1: I can do it:"sudo startx". But I can't login like username.
upd_2: I logined like root. Change pass. After that login like root in form login/pass. I have alert massege "/root/.profile have error stdin: is not tty" I'm in the X.