Mmmmh...
En fait on dirait que c'est déjà "radeon" qui est indiqué, bizarre, voici mon xorg.conf :
Xorg configuration created by system-config-display
Section "ServerLayout"
Identifier "single head configuration"
Screen 0 "Screen0" 0 0
InputDevice "Keyboard0" "CoreKeyboard"
EndSection
Section "InputDevice"
Identifier "Keyboard0"
Driver "kbd"
Option "XkbModel" "pc105"
Option "XkbLayout" "us"
EndSection
Section "Device"
Identifier "Videocard0"
Driver "radeon"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Videocard0"
DefaultDepth 24
SubSection "Display"
Viewport 0 0
Depth 24
EndSubSection
EndSection
ça veut dire que mon soucis vient d'ailleurs ?