lightdm doesn't start: Maximum number of clients reached

Here a video with all proccess.

http://www.youtube.com/watch?v=E7m4gbUJNbs

The problem seems be unity-greeter.

http://ubuntuforums.org/showthread.php?t=1871466

I had the same problem, and it was due to unity-greeter segfaulting (visible in /var/log/kern.log).

I purged unity-greeter and installed lightdm-gtk-greeter, and modified /etc/lightdm/lightdm.conf to use "greeter-session=lightdm-gtk-greeter".

It works.

Changed from lightdm to unity-greeter

Thank you for your bug report. Do you have indicator-datetime installed? Does it work better if you install it?

Yes I have it installed

$ apt-cache policy indicator-datetime
indicator-datetime:
  Installed: 0.3.1-0ubuntu5
  Candidate: 0.3.1-0ubuntu5
  Version table:
 *** 0.3.1-0ubuntu5 0
        500 http://archive.ubuntu.com/ubuntu/ precise/main i386 Packages
        100 /var/lib/dpkg/status

$ apt-cache policy lightdm-gtk-greeter
lightdm-gtk-greeter:
  Installed: 1.0.6-0ubuntu4
  Candidate: 1.0.6-0ubuntu4
  Version table:
 *** 1.0.6-0ubuntu4 0
        500 http://archive.ubuntu.com/ubuntu/ precise/universe i386 Packages
        100 /var/lib/dpkg/status

$ apt-cache policy unity-greeter
unity-greeter:
  Installed: 0.2.0-0ubuntu5
  Candidate: 0.2.0-0ubuntu5
  Version table:
 *** 0.2.0-0ubuntu5 0
        500 http://archive.ubuntu.com/ubuntu/ precise/main i386 Packages
        100 /var/lib/dpkg/status

ok, so it's different from bug #921998

I have the same problem described. In my case, none of the display managers will load because all of them fail with a segfault in libgio-2.0.so.0.3000.0. I have tried purging
all of the dm's and starting anew as well as changing lightdm config, but I still can't use a graphical display because of that one file that causes a problem in every
login program I use. I have also tried reinstalling the package that contains the .so file that is segfaulting (libglib2.0-0), but the file does not change at all.
I have the packages you describe installed. I am not sure how I can get my computer to function correctly.

However, something interesting is happening in my logs that I think may be related to this failure, or perhaps even the cause of the segfault. My ~/.xsession-errors log
file gives, in about 100 very specific lines detailing what exactly it can't load, the general impression that it can't connect to DBus. I am not sure if this is a common
error that happens when there is an X problem, or one that is a symptom of a more specific problem. I will upload my log files, see if you can take a look, and maybe tell
me how to temporarily at least how to get a working graphical environment.

I also forgot to mention that I have all of the symptoms described in the original post, as well as my findings.

Changing to confirmed because it affects me and another user, and because I assume the information that was missing was whether or not indicator-datetime was installed

As of a few hours ago, my DM actually loaded up, albeit with a few errors. Now, I have to figure out what I fixed. I'm going to try messing things up again and seeing if I can discover anything.