Same problem here (Edgy Eft Amd64). It happened because I have the nvidia proprietary drivers installed (this is why proprietary drivers are bad:))
To solve the problem, do the following: After your PC runs into the blue "X problem" screen, press Ctrl-Alt-F1 to go to the console in text mode. In the console, login, then type: sudo apt-get installlinux-restricted-modules-2.6.17-11-generic Reboot. Or, if you don't like to use the console and type commands do the following: When the PC start you have the choice to boot: Ubunt, kernel 2.6.17-11-generic Ubuntu, kernel 2.6.17-10-generic Choose kernel 2.6.17-10-generic, the PC will start normally. Log in and start Synaptic (System > Administration > Synaptic Package Manager) Search "nvidia" You will find: linux-restricted-modules-2.6.17-10-generic, that is installed and linux-restricted-modules-2.6.17-11-generic that is not installed Mark linux-restricted-modules-2.6.17-11-generic for installation and press Apply. Reboot. It seems this update should have been installed at the same time than the kernel 2.6.17-11.1 update, but wasn't. -- X wont start after upgrade to -11 kernel https://launchpad.net/bugs/84348 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs