I had the same problem today when i installed. I didn't see Advanced button or probably didn't pay attention to it and kept clicing next. On reboot it didn't find my user so had to create using root account.
I also have another issue with root account. After couple of reboots i couldn't logon using root account. No matter what i did it didn't take the root account. I did enter the right passwd each time and it worked only the first time when i created the regular user using root. I tried to enter into single user mode on boot but that didn't work either. I was about to post on this issue when i stumbled upon this post. Is this a bug??
Another issue that i had was i couldn't see restart/shutdown option anywhere. In the taskbar even though it showed red shutdown/restart button all it had was logout. Again after couple of reboots shutdown/restart automatically showed up.
Forgot to mention earlier - I did check integrity of the iso and it showed success.