There have been several people asking for the default username and password for the Ultimate Edition 4.2 live CD, since they can't get past that prompt. The username REALLY IS "ultimate" (all lower case) and the password REALLY IS "" (null, as in "enter"). I know, you tried and that didn't work. If you look closely you will notice the rejection message is different. It reads "Failed to start session" for the correct user/pass instead of "Invalid password, please try again". The problem is found at the end of /var/log/authlog. -it is the missing library /lib/security/pam_kwallet.so
It's not just you.