Atualizei o kernel e nada, vou postar as configurações do pc:
Placa Mãe - PCWARE IPM41-D2
Processador - Pentium Dual Core 2,70GHz
2GB DDR2
HD Samsung Sata 2 320GB
Vídeo onboard - Intel 4 Series Chipset G41 (GMA x4500)
Monitor - Proview XP 911AW
Ubuntu 12.04 LTS totalmente atualizado.
meu xorg:
_________________________________________________________________________________
# 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" "abnt2"
Option "XkbLayout" "br"
Option "XkbOptions" "lv3:ralt_switch"
EndSection
Section "InputDevice"
Identifier "Configured Mouse"
Driver "mouse"
Option "CorePointer"
EndSection
Section "Device"
Identifier "Configured Video Device"
EndSection
Section "Monitor"
Identifier "Configured Monitor"
EndSection
Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
SubSection "Display"
Depth 16
Modes "1440x900" "1024x768" "800x600" "640x480"
EndSubSection
EndSection
Section "ServerLayout"
Identifier "Default Layout"
Screen "Default Screen"
EndSection
quando coloquei esse xorg e reiniciei, ele carregou o sistema em low graphics mode.
desculpem se eu estiver fazendo alguma coisa errada