Merci mais je ne suis pas en mesure de répondre à ces questions car je ne suis qu'en mode console.
le contenu du fichier Xorg.0.log est :
[ 21025.683]
X.Org X Server 1.13.2
Release Date: 2013-01-24
[ 21025.684] X Protocol Version 11, Revision 0
[ 21025.685] Build Operating System: 2.6.32-279.19.1.el6.x86_64
[ 21025.685] Current Operating System: Linux tiramisu 3.7.7-201.fc18.x86_64 #1 SMP Tue Feb 12 22:35:01 UTC 2013 x86_64
[ 21025.685] Kernel command line: BOOT_IMAGE=/vmlinuz-3.7.7-201.fc18.x86_64 root=/dev/mapper/vg_tiramisu-lv_root ro rd.md=0 rd.dm=0 rd.lvm.lv=vg_tiramisu/lv_root LANG=fr_FR.UTF-8 rd.lvm.lv=vg_tiramisu/lv_swap rd.luks=0 SYSFONT=True KEYTABLE=fr-latin9 rhgb quiet
[ 21025.686] Build Date: 26 January 2013 04:43:27AM
[ 21025.687] Build ID: xorg-x11-server 1.13.2-2.fc18
[ 21025.687] Current version of pixman: 0.26.2
[ 21025.688] Before reporting problems, check http://wiki.x.org
to make sure that you have the latest version.
[ 21025.688] Markers: (--) probed, (**) from config file, (==) default setting,
(++) from command line, (!!) notice, (II) informational,
(WW) warning, (EE) error, (NI) not implemented, (??) unknown.
[ 21025.690] (==) Log file: "/var/log/Xorg.0.log", Time: Sat Feb 16 17:35:35 2013
[ 21025.691] (==) Using config directory: "/etc/X11/xorg.conf.d"
[ 21025.691] (==) Using system config directory "/usr/share/X11/xorg.conf.d"
[ 21025.691] (==) No Layout section. Using the first Screen section.
[ 21025.691] (==) No screen section available. Using defaults.
[ 21025.691] (**) |-->Screen "Default Screen Section" (0)
[ 21025.691] (**) | |-->Monitor "<default monitor>"
[ 21025.691] (==) No device specified for screen "Default Screen Section".
Using the first device section listed.
[ 21025.691] (**) | |-->Device "Videocard666"
[ 21025.691] (==) No monitor specified for screen "Default Screen Section".
Using a default monitor configuration.
[ 21025.691] (==) Automatically adding devices
[ 21025.691] (==) Automatically enabling devices
[ 21025.691] (==) Automatically adding GPU devices
[ 21025.691] (==) FontPath set to:
catalogue:/etc/X11/fontpath.d,
built-ins
[ 21025.691] (==) ModulePath set to "/usr/lib64/xorg/modules"
[ 21025.691] (II) The server relies on udev to provide the list of input devices.
If no devices become available, reconfigure udev or disable AutoAddDevices.
[ 21025.691] (II) Loader magic: 0x801ce0
[ 21025.691] (II) Module ABI versions:
[ 21025.691] X.Org ANSI C Emulation: 0.4
[ 21025.691] X.Org Video Driver: 13.1
[ 21025.691] X.Org XInput driver : 18.0
[ 21025.691] X.Org Server Extension : 7.0
[ 21025.692] (II) config/udev: Adding drm device (/dev/dri/card0)
[ 21025.693] (--) PCI:*(0:2:0:0) 10de:0641:0000:0000 rev 161, Mem @ 0xfd000000/16777216, 0xd0000000/268435456, 0xfa000000/33554432, I/O @ 0x0000ec00/128, BIOS @ 0x????????/524288
[ 21025.693] Initializing built-in extension Generic Event Extension
[ 21025.694] Initializing built-in extension SHAPE
[ 21025.694] Initializing built-in extension MIT-SHM
[ 21025.694] Initializing built-in extension XInputExtension
[ 21025.695] Initializing built-in extension XTEST
[ 21025.695] Initializing built-in extension BIG-REQUESTS
[ 21025.696] Initializing built-in extension SYNC
[ 21025.696] Initializing built-in extension XKEYBOARD
[ 21025.696] Initializing built-in extension XC-MISC
[ 21025.697] Initializing built-in extension XINERAMA
[ 21025.697] Initializing built-in extension XFIXES
[ 21025.698] Initializing built-in extension RENDER
[ 21025.698] Initializing built-in extension RANDR
[ 21025.698] Initializing built-in extension COMPOSITE
[ 21025.699] Initializing built-in extension DAMAGE
[ 21025.699] Initializing built-in extension MIT-SCREEN-SAVER
[ 21025.699] Initializing built-in extension DOUBLE-BUFFER
[ 21025.700] Initializing built-in extension RECORD
[ 21025.700] Initializing built-in extension DPMS
[ 21025.700] Initializing built-in extension X-Resource
[ 21025.701] Initializing built-in extension XVideo
[ 21025.701] Initializing built-in extension XVideo-MotionCompensation
[ 21025.701] Initializing built-in extension SELinux
[ 21025.702] Initializing built-in extension XFree86-VidModeExtension
[ 21025.702] Initializing built-in extension XFree86-DGA
[ 21025.702] Initializing built-in extension XFree86-DRI
[ 21025.703] Initializing built-in extension DRI2
[ 21025.703] (II) LoadModule: "glx"
[ 21025.703] (II) Loading /usr/lib64/xorg/modules/extensions/libglx.so
[ 21025.703] (II) Module glx: vendor="X.Org Foundation"
[ 21025.703] compiled for 1.13.2, module version = 1.0.0
[ 21025.703] ABI class: X.Org Server Extension, version 7.0
[ 21025.703] (==) AIGLX enabled
[ 21025.704] Loading extension GLX
[ 21025.704] (II) LoadModule: "vboxvideo"
[ 21025.704] (II) Loading /usr/lib64/xorg/modules/drivers/vboxvideo_drv.so
[ 21025.704] (II) Module vboxvideo: vendor="Oracle Corporation"
[ 21025.704] compiled for 1.13.1, module version = 1.0.1
[ 21025.704] Module class: X.Org Video Driver
[ 21025.704] ABI class: X.Org Video Driver, version 13.1
[ 21025.704] (**) Load address of symbol "VBOXVIDEO" is 0x7f7481d33420
[ 21025.704] (II) VBoxVideo: guest driver for VirtualBox: vbox
[ 21025.704] (--) using VT number 1
[ 21025.707] (EE) No devices detected.
[ 21025.707]
Fatal server error:
[ 21025.707] no screens found
[ 21025.707] (EE)
Please consult the Fedora Project support
at http://wiki.x.org
for help.
[ 21025.707] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
[ 21025.707] (EE)
Je constate qu'il y a un problème d'écran. A priori, il faut modifier le fichier xorg.conf mals je ne sais pas où le trouver.
Merci de votre aide.