I too had trouble after installing VL7. In the first instance I was able to use my password to enter the user account but could not enter root with the the password I created. I installed VL7 three times using the GUI installer all with the same result, could not access root using my root password. The fourth time I installed VL7 Live. This time I could not enter user or root using my created passwords. In VL7 Live the default root password is blank so I tried that to get into root after the install. IT WORKED. Now I had a clue to what was wrong. I then reinstalled VL7 STD GOLD setting root and user passwords as the installer asked. But once again at the login screen they didn't work. I entered root by hitting enter when it asked for a password. Then, as root, I opened VASM and changed root's password to the one I wanted to use. Then I tried to do the same for user but that account was not even created. I had to create a new user account. That worked fine. So now I have a full install where I can enter root and user with my own passwords. I hope this helps others who had the same experience.
edit five hours later: I was tired last night from being at the computer so long. I forgot to say that the last install I used the old installer not the new GUI installer. The old installer is available by typing install at the first prompt when booting the disk. That means I don't know if my solution will also work with the new GUI installer. Another person will have to try that. I will work with what I now have. Good Luck.