It's hard to believe how many postings you can find when searching the internet on Nvidia with Ubuntu problems, yet here goes one more:
I have a NVIDIA GeForce GT 430 video card and a 32bit AMD machine. I'm dual booting Windows 7 with Ubuntu 12.04 LTS. I've tried many different ways of installing both the NVIDIA proprietary and Ubuntu packaged drivers as suggested by many different postings. When things don't work, I get a black screen, or a screen with the default GUI background with no icons.
More often than not, the driver (both NVIDIA and Nouveau?) installation DOES appear to work. What happens is I get a nice hi-res view of the desktop, much better resolution than what I see when using the Live CD. Some apps work perfectly (Dash, Home, Firefox, and all of the Libre apps). Other apps (system settings, appearance, software center etc.), an icon appears in the launcher with a ">" within or next to the icon. When you point to that icon, it wiggles, but that's about it. No error message, and no app appears.
I've spent hours trying to get this to work, and I don't give up easily, and I'm looking for suggestions that will get all functions working. Thanks in advance.