merci pour ta réponse
xubu1957
Je suis allé dans le fichier indiqué
sudo leafpad /etc/lxdm/default.conf
mais malheureusement numlock était déjà à 1, donc ce n'est pas ça non plus.
un peu une histoire de fous cette galère.
[base]
## uncomment and set autologin username to enable autologin
autologin=micronet
## uncomment and set timeout to enable timeout autologin,
## the value should >=5
# timeout=10
## default session or desktop used when no systemwide config
session=/usr/bin/startlubuntu
## uncomment and set to set numlock on your keyboard
numlock=1
## set this if you don't want to put xauth file at ~/.Xauthority
# xauth_path=/tmp
## greeter used to welcome the user
greeter=/usr/lib/lxdm/lxdm-greeter-gtk
[server]
## arg used to start xserver, not fully function
# arg=/usr/bin/X -background vt1
[display]
## gtk theme used by greeter
gtk_theme=Clearlooks
## background of the greeter
bg=/usr/share/lubuntu/wallpapers/lubuntu-default-wallpaper.png
## if show bottom pane
bottom_pane=1
## if show language select control
lang=1
## if show keyboard layout select control
keyboard=0
## the theme of greeter
theme=Lubuntu
[input]
[userlist]
## if disable the user list control at greeter
disable=0
## whitelist user
white=
## blacklist user
black=
