6.2.1 .xsession-errors

[mecho]

Yor second command has a typo: ls -l ./.config/autostart should be ls -l ~/.config/autostart
And your 3rd command is wrong.

Do it the following way:
ls -l ~/.config/autostart
ls -l /etc/xdg/autostart
cat -n /etc/xdg/lxsession/LXDE/autostart

The 3rd one is lxsession autostart file which probably contains 1 instance of polkit and I can see that you already have one in /etc/xdg/autostart/
If cat -n /etc/xdg/lxsession/LXDE/autostart prints polkit line, then it is safe to delete
/etc/xdg/autostart/polkit-gnome-authentication-agent-1.desktop
and
/home/knoppix/.config/autostart/polkit-gnome-authentication-agent-1.desktop
Only leave the starting line in /etc/xdg/lxsession/LXDE/autostart and you will be fine