I just installed ubuntu-12.04-desktop-i386.iso to my 1GB flash drive via Startup Disk Creator on Ubuntu 12.04. Then, I tried to boot it on my system.
The problem is that it was asking me for username and password.
I tried "ubuntu" with blank password but it didn't work.
The problem has never happened when I installed the same iso file via Universal USB Installer on Windows.
Note: There's no option to make passwords in Startup Disk Creator.