Comment 1 for bug 78963

Thanks for the report,

 This is actually a pretty common issue with a lot of video cards ATI & Nividia, in fact I experienced it myself on my laptop with an ATI card.

 One option you can try is booting up in recovery mode and modifying your /etc/X11/xorg.conf file and where it says:

Section "Device"
Identifier "Your Nvidia Card"
Driver "Nv"

At least I think it is nv, anways change whatever that is to vesa, save it then try to boot up again. This will just get you into the gui but you'll still have to install proprietary drivers. Changing it to vesa actually froze for me... but it works for some. I installed my proprietary drivers through the recovery mode console.

For instructions on how to accomplish this you can refer to:

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

The page says it's for dapper but I don't really see anything that wouldn't work in Edgy or Feisty. This worked for me, hopefully it will work for you.