Ubuntu is running in low-graphics mode

These days, it is too busy to post something on my blog.

But I like this project which I could not talk about.

After I changed my desktop monitor, display went unstable.
Finally, after rebooting, I met “Ubuntu is running in low-graphics mode”.

For my Radeon HD 4350, I installed latest ATI driver again, but nothing was improved.

ATI HowTo from ubuntu documentation couldn’t help me.

https://help.ubuntu.com/community/Video

https://help.ubuntu.com/community/BinaryDriverHowto/ATI

$ fglrxinfo
==>returned null display.

I found the Q&A thread “[SOLVED] Stuck in Low graphics mode.” & solved the issue. Thanks, warp99

http://ubuntuforums.org/archive/index.php/t-748716.html

I think the point is resintalling gdm(GNOME display manager).

sudo apt-get update
make sure the update runs to remove the previous repositories then:
sudo apt-get -d install --reinstall gdm
this will only download gdm to our archive, make sure the operation completes correctly before moving to the next step
sudo apt-get remove --purge gdm
when the package is being removed go ahead and stop xserver as the prompts says, then:
sudo apt-get install gdm
Now we have the new gdm installed with a new configuration, next we need to get rid of xgl and the associated files:
sudo apt-get remove --purge xserver-xgl compiz compiz-plugins compiz-core compiz-manager csm cgwd cgwd-themes
then install the following:
sudo apt-get install --reinstall compiz compiz-core compiz-fusion-plugins-extra compiz-fusion-plugins-main compiz-gnome compiz-plugins libcompizconfig0
and finally enter:
sudo dpkg-reconfigure -phigh xserver-xorg
choose the driver 'ati' and when you get to monitor resolution choose the resolution you want to run and any resolution ABOVE that resolution should be removed. Once that is done issue the following:
sudo reboot