我有一台采用 nvidia optimus 技术的笔记本电脑。我安装了 bumblebee，一切似乎都运行良好。问题是，当我登录后将第二台显示器连接到笔记本电脑时，它运行良好，但当我启动连接了显示器的笔记本电脑时，Xserver 无法启动。如何配置 xserver 使其工作？
这是我的硬件配置：
$ xrandr -q
Screen 0: minimum 320 x 200, current 3040 x 900, maximum 8192 x 8192
LVDS1 connected 1600x900+1440+0 (normal left inverted right x axis y axis) 382mm x 214mm
1600x900 60.0*+
1440x900 59.9
1360x768 59.8 60.0
1152x864 60.0
1024x768 60.0
800x600 60.3 56.2
640x480 59.9
VGA2 connected 1440x900+0+0 (normal left inverted right x axis y axis) 410mm x 256mm
1440x900 59.9*+
1280x1024 75.0 60.0
1152x864 75.0
1280x720 75.0 60.0
1024x768 75.1 70.1 60.0
832x624 74.6
800x600 72.2 75.0 60.3 56.2
640x480 72.8 75.0 66.7 60.0
720x400 70.1
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
编辑：这是我的 Horg.log
[ 15.921] (==) Log file: "/var/log/Xorg.0.log", Time: Sat Jan 7 23:00:34 2012
[ 15.921] (==) Using config file: "/etc/X11/xorg.conf"
[ 15.921] (==) Using system config directory "/usr/share/X11/xorg.conf.d"
[ 15.921] (==) No Layout section. Using the first Screen section.
[ 15.921] (==) No screen section available. Using defaults.
[ 15.921] (**) |-->Screen "Default Screen Section" (0)
[ 15.921] (**) | |-->Monitor "<default monitor>"
[ 15.921] (==) No device specified for screen "Default Screen Section".
Using the first device section listed.
[ 15.921] (**) | |-->Device "Default Device"
[ 15.921] (==) No monitor specified for screen "Default Screen Section".
Using a default monitor configuration.
[ 15.921] (==) Automatically adding devices
[ 15.921] (==) Automatically enabling devices
[ 15.921] (WW) The directory "/usr/share/fonts/X11/cyrillic" does not exist.
[ 15.921] Entry deleted from font path.
[ 15.921] (WW) The directory "/usr/share/fonts/X11/100dpi/" does not exist.
[ 15.921] Entry deleted from font path.
[ 15.921] (WW) The directory "/usr/share/fonts/X11/75dpi/" does not exist.
[ 15.921] Entry deleted from font path.
[ 15.921] (WW) The directory "/usr/share/fonts/X11/100dpi" does not exist.
[ 15.921] Entry deleted from font path.
[ 15.921] (WW) The directory "/usr/share/fonts/X11/75dpi" does not exist.
[ 15.921] Entry deleted from font path.
[ 15.921] (==) FontPath set to:
/usr/share/fonts/X11/misc,
/usr/share/fonts/X11/Type1,
/var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType,
built-ins
[ 15.921] (==) ModulePath set to "/usr/lib/x86_64-linux-gnu/xorg/extra-modules,/usr/lib/xorg/extra-modules,/usr/lib/xorg/modules"
[ 15.921] (II) The server relies on udev to provide the list of input devices.
If no devices become available, reconfigure udev or disable AutoAddDevices.
[ 15.921] (II) Loader magic: 0x7e0220
[ 15.921] (II) Module ABI versions:
[ 15.921] X.Org ANSI C Emulation: 0.4
[ 15.921] X.Org Video Driver: 10.0
[ 15.921] X.Org XInput driver : 12.3
[ 15.921] X.Org Server Extension : 5.0
我的 xorg.conf 几乎是空的：
Section "Device"
Identifier "Default Device"
Option "NoLogo" "True"
EndSection
如何配置 Xorg 使其工作？