Intel GMA adapter support seems to be known to be problematic.
I turned off fancy graphics. Seems to fix it for me.
-Change Desktop Background
Note 1. Ctrl-Al-Backspace to restart X is disabled. You should re-enabled it.
Enabling Ctrl-Alt-Backspace for Ubuntu 10.04http://www.ubuntugeek.com/enable-ctrl-alt-backspace-in-ubuntukubuntu-10-04lucid-lynx.html
* Select “System”->”Preferences”->”Keyboard”
* Select the “Layouts” tab and click on the “Layout Options” button.
* Select “Key sequence to kill the X server” and enable “Control + Alt + Backspace”.