I am working on my 2nd mackintosh and this one has a very interesting problem... I can log into the root account just fine, however, I set up an administrator account. From the login screen (set to username and password for root access) if I type the administrator user and pass, I get to look at a spinning 'gear' and the spinning mouse cursor on a blurred yosemite background for as long as I please. If I use the root user and pass it logs me in fairly quickly.
This is my 3rd fresh install, the first two were useless because I couldn't log in after the initial setup. I now have it set to user and pass login form so I can use the root account and iron out tricky drivers for a while.
HP Pavillon dv6 Notebook:
Unfortunately I don't know much about the computer, it is a friends of mine...