Comment 13 for bug 233787

At first please post a current Xorg.0.log with your new xorg.conf to see the difference.
It is the best to report it upstream I guess but could you please check if this issue still happens with the unofficial package http://people.ubuntu.com/~bryce/Testing/intel/hardy-amd64/xserver-xorg-video-intel_2.3.1-1ubuntu1~bwh3_amd64.deb of a newer -intel driver.

To install it you have to remove the old i810 driver before.
sudo apt-get remove xserver-xorg-video-i810 xserver-xorg-video-all

And please regenerate your xorg.conf just to be sure.
sudo dpkg-reconfigure xserver-xorg

If you want to reset everything do the follow commands.
sudo apt-get remove xserver-xorg-video-intel
sudo apt-get install xserver-xorg-video-all

Of course you have to uncomment your current xorg.conf options before X restart.