bonjour, 
essaie cette commande
# apt-get install xserver-xorg-video-intel
si il est deja installer,tente:
# apt-get install --reinstall xserver-xorg-video-intel
puis tu redemarres
je te garantie rien ,je n’ai jamais eu le cas
sinon je te poste mon /etc/X11/xorg.conf
[code]# xorg.conf (X.Org X Window System server configuration file)
This file was generated by dexconf, the Debian X Configuration tool, using
values from the debconf database.
Edit this file with caution, and see the xorg.conf manual page.
(Type “man xorg.conf” at the shell prompt.)
This file is automatically updated on xserver-xorg package upgrades only
if it has not been modified since the last upgrade of the xserver-xorg
package.
If you have edited this file but would like it to be automatically updated
again, run the following command:
sudo dpkg-reconfigure -phigh xserver-xorg
Section “InputDevice”
Identifier “Generic Keyboard”
Driver “kbd”
Option “XkbRules” “xorg”
Option “XkbModel” “pc105”
Option “XkbLayout” “fr”
Option “XkbVariant” “latin9”
EndSection
Section “InputDevice”
Identifier “Configured Mouse”
Driver “mouse”
EndSection
Section “Device”
Identifier “Configured Video Device”
EndSection
Section “Monitor”
Identifier “Configured Monitor”
EndSection
Section “Screen”
Identifier “Default Screen”
Monitor “Configured Monitor”
EndSection[/code]
le copier/coller pourrait retablir la resolution
une autre possibilité
# dpkg-reconfigure -phigh xserver-xorg