Ubuntu is running in low-graphics mode

Ubuntu is running in low-graphics mode: 

Make sure the update runs to remove the previous repositories then:

sudo apt-get update

This will only download gdm to our archive, make sure the operation completes

 correctly before moving to the next step:

sudo apt-get -d install --reinstall gdm

When the package is being removed go ahead and stop xserver as the prompts says, then:

sudo apt-get remove --purge 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 install gdm

Then install the following:

sudo apt-get remove --purge xserver-xgl compiz compiz-plugins
 compiz-core compiz-manager csm cgwd cgwd-themes

And  

sudo apt-get install --reinstall compiz compiz-core
 compiz-fusion-plugins-extra compiz-fusion-plugins-main
 compiz-gnome compiz-plugins libcompizconfig0

Remove existing xorg using the following command

sudo apt-get remove --purge xserver-xorg

 Install xorg using the following command

 sudo apt-get install 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 dpkg-reconfigure -phigh xserver-xorg

sudo reboot