The Dell Inspiron 6400 with an ATI video card, Dell Inspiron 8600 with an Nvidia 5200 card, Dell Latitude D620 with Nvidia Quadro NVS 110M video card, and Hewlett-Packard NX6125 are among the systems reported as being bitten by this bug.
One workaround being posted on Wikis is to downgrade to the previous version of Xorg by entering the following commands:
sudo apt-get install xserver-xorg-core=1:1.0.2-0ubuntu10 sudo /etc/init.d/gdm restart
A better workaround appears to be upgrading to xorg-server 1:1.0.2-0ubuntu10.4, after verifying that it is available in your repositories. To check and see if it is available to you, use the following commands:
sudo apt-get update apt-cache -f search xserver-xorg-core
If the 10.4 version listed, then proceed with:
sudo apt-get upgrade
Of course, if you haven't upgraded to 10.3 yet, don't.