В xorg.conf. install вообще бред какойто, видно его вообще VirtualBox создал что ли ?
Section "Device"
Identifier "vboxvideo"
Driver "vboxvideo"
EndSection
Section "Screen"
Identifier "vboxvideo"
Device "vboxvideo"
EndSection
Section "Device"
Identifier "vmware"
Driver "vmware"
EndSection
Section "Screen"
Identifier "vmware"
Device "vmware"
EndSection
Section "Device"
Identifier "cirrus"
Driver "cirrus"
EndSection
Section "Screen"
Identifier "cirrus"
Device "cirrus"
EndSection
Section "Device"
Identifier "fbdev"
Driver "fbdev"
EndSection
Section "Screen"
Identifier "fbdev"
Device "fbdev"
EndSection
Section "Device"
Identifier "vesa"
Driver "vesa"
EndSection
Section "Screen"
Identifier "vesa"
Device "vesa"
EndSection
Section "ServerLayout"
Identifier "Layout"
Screen "vboxvideo"
Screen "vmware"
Screen "cirrus"
Screen "fbdev"
Screen "vesa"
EndSection