I started having this issue after having removed Kubuntu from my computer. At first login screen wouldn't even show, instead the screen stopped at
Checking Battery state stage. At this point I still could use
startx after Alt+F1. Then I reinstalled and reconfigured dmg and
ubuntu-desktop a number of times, so I got my login screen back. Now, everytime I get to the login screen, my user name shows up but password is not requested, just an 'Access' button shows, and if I click the button the screen just goes black for a second and then I'm back to the login screen. I can get into Ubuntu only via Guest account. In addition, Alt+F1 and
startx doesn't work anymore, giving me an output that ends like this:
xinit: unable to connect to X server: Connection refused xinit: server error
Since I believe this is somehow related to an X issue, I took a log of
Xorg.0.log, here is the link.
Hope someone has a solution.