Comment 4 for bug 568096

Somehow (and ive no idea how as this notebook has an intel graphics chipset) the nvidia drivers got installed during the upgrade to lucid from karmic. After fixing the drivers, the graphics went back to normal. This may not solve the Op's issue, but i thought id post this here incase.

sudo apt-get purge nvidia*
sudo apt-get install --reinstall xserver-xorg-video-intel libgl1-mesa-glx libgl1-mesa-dri xserver-xorg-core
sudo dpkg-reconfigure xserver-xorg
sudo update-alternatives --remove gl_conf /usr/lib/nvidia-current/ld.so.conf
sudo reboot