I have this headache several times when i use apt-get upgrade since 2002 and reinstalled my system many times I am searching a answer for this question and I found this page http://www.5z.com/jirka/gdm-documentation/x84.html at this link I read "The output from the user session is redirected to ~/.xsession-errors" the I searched this file Eureka !!!! the erros was cannot found /etc/X11/Xsession script !!!!!!! for my luck , there is a file Xsession.dpkg-old that directory and I copied with Xsessi...