I have an acer with a Gforce graphics card. I installed ubuntu 11.10 and it was working properly until I installed Nvidia drivers via additional drivers, I hit "nvidia-xconfig" in terminal and then reboot. At startup lightdm fails to start. I changed /etc/X11/xorg.conf file back to default and reboot. It works properly, but with the default Ubuntu driver. I want to reconfigure Nvidia and use it. Can anyone tell me what should I do?