Before installing nvidia drivers from software-properties-gtk, I had problem when ubuntu starts..
I get a plain purple screen after which I get the login screen.
While shut down I get the usual Ubuntu screen (the purple screen with Ubuntu written and an animation indicating that shutdown /restart process is going on)

After installing the nvidia drivers, I get a text "Ubuntu 12.10" with no loading animation. and sometimes I get it with a black background on it. And while shutting down, I just get my screen blanked. No acknowledgement about the Ubuntu getting shut down. I've to to look at the Power LED to make sure my PC is turned off...

Is that something to do with/related to the brightness issue ???