X no longer starts automatically

view story

http://serverfault.com – I installed some software on my CentOS 6.3 virtual machine (under VMWare Workstation). And after rebooting, the X (GNOME) don't start automatically. I can cause to start X using startx command. But when I try to switch user (from started GNOME) I get an exception in graphical window(GNOME don't crash, only error message in popup) : The name org.gnome.DisplayManager was not provided by any .service files And when I try to logout X crashes and instead X opens command line with following messages: Where is problem? How to solve it? (HowTos)