Comment 11 for bug 483857

@Daniel Wejse,

You should open your xorg.conf file, not the one that you downloaded. It's usually in the /etc/X11 folder. Do these steps:

Open a terminal (Applications > Accessories > Terminal) and type the following commands:
sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf.backup
sudo gedit /etc/X11/xorg.conf

Now, in the editor window, find the following text:

Driver "nvidia"

and add the following line between the Option "No Logo" "True" and the End Section lines:

Option "ModeValidation" "NoTotalSizeCheck"

Now save the file and reboot.

If you have any problems you can revert this by opening a terminal and executing

sudo cp /etc/X11/xorg.conf.backup /etc/X11/xorg.conf

and rebooting again.

BTW, this solution worked for me as well. I own an Acer Extensa 5635ZG, thanks Camilla!!

HTH