Perhaps if users end up here, this little guide could help some people overcome this problem. I had this problem myself, with nvidia hardware.
I have Nvidia video hardware and had the flashing problem when I updated to 9.10. I suspect that the flashing is caused by the gdm service trying to repeatedly start the X server over and over, but it fails to start, so it keeps retrying, which causes the flashing. When it is flashing, nothing is properly working including the keyboard, so I had to force a reboot by holding down the power button for 10 seconds to force it off, then powering it up again a few seconds later. Boot the Ubuntu live CD, sudo to root: sudo su - Then use this command to display the drive's partition table (your install could be on a different drive, eg /dev/sdb but most are probably /dev/sda, that's a lower case L as option): fdisk -l /dev/sda I then mounted the partition where the etc directory for the install is found: mkdir /stuff (a place to mount it) mount /dev/sda5 /stuff (this will likely be different for you, you'll have to choose the right linux partition): and moved /etc/X11/xorg.conf aside: cd /stuff/etc/X11 mv -i xorg.conf xorg.conf.fails Then created a new xorg.conf: cat >xorg.conf <<EOF Section "Device" Identifier "Configured Video Device" EndSection Section "Monitor" Identifier "Configured Monitor" EndSection Section "Screen" Identifier "Default Screen" Monitor "Configured Monitor" Device "Configured Video Device" EndSection EOF I then unmounted the partition: cd / umount /stuff then rebooted (and removed the bootable cd): reboot Once rebooted the flashing no longer happens, but you're running the open source video driver, which works but doesn't give the best result. If you're wanting to use Ubuntu to set up the closed source driver, you can logon and let it inform you that the closed source driver can be used, proceed that way, and it should all be automatic. If you're wanting to use a driver that is more recent than what ubuntu provides, then you can download it, and use the following steps: Once you've got the login screen, press CTRL-ALT-F1 and logon Then become root: sudo su - Then stop the gdm service because the driver install needs X to be down while installing: service gdm stop Then run the nvidia installer and proceed the install Once installed you can do this: service gdm start And your X server should be up and running then with the nvidia driver. You can flick back to the console window with CTRL-ALT-F1 and logout, then flick back to X with CTRL-ALT-F7. -- upgrade breaks graphic drivers and x, preventing login or startx https://bugs.launchpad.net/bugs/464591 You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in ubuntu. _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp