@Mecho

Thanks for your reply.
Here's what I get for the polkit suggestion.

#### Regarding /etc/xdg/autostart:
knoppix@Microknoppix:/$ ls -l /etc/xdg/autostart gives
total 8
-rw-r--r-- 1 root root 4831 Jan 26 23:53 nm-applet.desktop
-rw-r--r-- 1 root root 2531 Jan 15 23:40 polkit-gnome-authentication-agent-1.desktop

#### Regarding ~/.config/autostart:
knoppix@Microknoppix:~$ ls -l ./.config/autostart gives
total 12
-rw-r--r-- 1 knoppix knoppix 4832 Jul 7 09:05 nm-applet.desktop
-rw-r--r-- 1 knoppix knoppix 2532 Jul 7 09:05 polkit-gnome-authentication-agent-1.desktop

#### Regarding /etc/xdg/lxsession/LXDE/autostart:
knoppix@Microknoppix:/etc/xdg/autostart$ ls -l /etc/xdg/autostart gives
total 8
-rw-r--r-- 1 root root 4831 Jan 26 23:53 nm-applet.desktop
-rw-r--r-- 1 root root 2531 Jan 15 23:40 polkit-gnome-authentication-agent-1.desktop

Does this tell you anything?
I have no idea what this means.