Your comment about the Live cd worries me a bit, normally that phrase means it's not an install but just a copy of the OS on DVD that you can boot on any computer, then when finished just eject and reboot to go back to the previous OS again (ie it doesn't install and seldom touches the hard drive even)
But if you really have installed it, try the following:
Change CAPSLOCK (if it was on, turn it off, if it was off, turn it on) and type the password again.
Try root/<nothing> (ie just hit enter on the password prompt)
Try your username/<nothing>
If all that fails, you *can* reset the password by booting off the cd, mounting the root filesystem and editing the password file (or chrooting a passwd call) but I suspect that might be a bit complex to talk you through here. If you are still stuck at this point, I'd just go for a reinstall
