Did you do a fresh install of Fedora Core 6, please?
Yes.
I have installed xorg-x11-xdm so /etc/X11/xdm/Xservers look likes this: :0 local /usr/bin/X :2 local /usr/bin/X I did reset X server, but I continue with only one X window. Any ideas, please?
Not sure. I have always used GDM (since FC2). In Gnome: System->Login Screen, then the 'Security' tab, then the 'Configure X Server' button - then add/delete servers as necc. HTH, Chris