VIIIIINDIOUUUU !!! Ca marche, t’as raison, dans ce fichier j’ai une copie du fichier xorg.conf qui est utilisé par défaut et qui marche !! J’ai juste eu à rajouter une section keyboard avec ce que je veux dedans … Merci beaucoup à tous pour votre aide précieuse 
Bon juste pour le fun je met l’extrait du fichier /var/log/Xorg.0.log qui contient le xorg.conf par défaut qui marche :
Running "getconfig -X 70101000 -I /etc/X11,/usr/etc/X11,/usr/lib/xorg/modules,/usr/lib/X11/getconfig -v 0x10de -d 0x0426 -r 0xa1 -s 0x104d -b 0x9016 -c 0x0300"
(==) Using default built-in configuration (43 lines)
(==) --- Start of built-in configuration ---
Section "Module"
Load "extmod"
Load "dbe"
Load "glx"
Load "freetype"
EndSection
Section "Monitor"
Identifier "Builtin Default Monitor"
Option "TargetRefresh" "75.0"
EndSection
Section "Device"
Identifier "Builtin Default fbdev Device 0"
Driver "fbdev"
EndSection
Section "Screen"
Identifier "Builtin Default fbdev Screen 0"
Device "Builtin Default fbdev Device 0"
Monitor "Builtin Default Monitor"
EndSection
Section "Device"
Identifier "Builtin Default vesa Device 0"
Driver "vesa"
EndSection
Section "Screen"
Identifier "Builtin Default vesa Screen 0"
Device "Builtin Default vesa Device 0"
Monitor "Builtin Default Monitor"
EndSection
Section "Device"
Identifier "Builtin Default vga Device 0"
Driver "vga"
EndSection
Section "Screen"
Identifier "Builtin Default vga Screen 0"
Device "Builtin Default vga Device 0"
Monitor "Builtin Default Monitor"
EndSection
Section "ServerLayout"
Identifier "Builtin Default Layout"
Screen "Builtin Default fbdev Screen 0"
Screen "Builtin Default vesa Screen 0"
Screen "Builtin Default vga Screen 0"
EndSection
(==) --- End of built-in configuration ---
Et voila le xorg.conf que j’ai fait :
[size=70][code]Section "Files"
RGBPath "/etc/X11/rgb.txt"
ModulePath "/usr/lib/xorg/modules/"
EndSection
Section "InputDevice"
Identifier "Keyboard 1"
Driver "kbd"
Option "CoreKeyboard"
Option “XkbRules” "xorg"
Option “XkbModel” "pc105"
Option “XkbLayout” "fr"
Option “XkbVariant” "latin9"
EndSection
Section "InputDevice"
Identifier "Mouse 1"
Driver "mouse"
Option “Device” "/dev/input/mouse0"
Option "CorePointer"
Option “Protocol” "ExplorerPS/2"
Option “SendCoreEvents” "true"
Option “Emulate3Buttons” "true"
Option “Emulate3Timeout” "80"
Option “ZAxisMapping” "4 5"
Option “Sensitivity” "1"
EndSection
Section "InputDevice"
Identifier "TouchPad 1"
Driver "synaptics"
Option “Device” "/dev/input/mouse1"
Option “SendCoreEvents” "true"
Option “HorizScrollDelta” "1"
EndSection
Section "Device"
Identifier "geforce 8400M GT"
Driver "nv"
BusID "PCI:1:0:0"
Option “UseFBDev” "true"
EndSection
Section "Monitor"
Identifier "Monitor 1"
Option "DPMS"
EndSection
Section "Screen"
Identifier "Screen 1"
Device "geforce 8400M GT"
Monitor "Monitor 1"
DefaultDepth 24
SubSection "Display"
Depth 24
Modes "1440x900"
EndSubSection
EndSection
Section "ServerLayout"
Identifier "Default Layout"
Screen "Screen 1"
InputDevice "Keyboard 1"
InputDevice "Mouse 1"
InputDevice "TouchPad 1"
EndSection
Section "DRI"
Mode 0666
EndSection[/code][/size]