I see you have 2 gfx cards. Discrete cards or optimus?Can you switch to virtual console when the screen goes black? Ctrl+Alt+F2 and log in?Do you have package 'firmware-linux-nonfree' installed?
I've just installed ubuntu 11.10 on a 64bit machine with 2 nvidia cards. After installation, I rebooted and a black screen showed up, with a blinking white underscore. So I re installed the system, giving nomodeset as kernel boot option (since i understood it can solve this issue).
Now i dont have a black screen, but a corrupted splash screen with no login menu. CTrl+alt+F4 does nothing.
While using chromium normally, some URL's cause my computer to go black screen. Computer works fine but cant see anything. Can change to console using CTRL+ Alt + F1 but still black screen (I think the screen is shut down). I had to reboot using Ctrl + Alt + Del.
Is this a chromium bug? The URL's in question seem to have some sort of animation.