as stated, when using SLIM login manager, as soon as username and password are inputted, you are looped back to the login screen. You will not be able to run your DE.
Since SLIM runs ~/.xinitrc instead or .xsession like others and passes the session as an argument, the command line to run session from .xinitrc becomes invalid causing Xorg to fail to run.
the culprit is these lines
# # Try consolekit
if 66-which -q ck-launch-session; then
cmd="exec ck-launch-session $@ "
else
cmd="exec $@ "
fi
# # Select the session to start
${cmd} openbox-session
For example, if you want to run openbox, the "$@ " will take up the argument, in this case the session openbox-session making the final ${cmd} line to be
exec ck-launch-session "openbox-session" openbox-session
or
exec "openbox-session" openbox-session