I have followed your tips and the output is:
nautilus: no process killed

The screen is still black.

Now your black screen will be fixed. If not, you may be experiencing additional (and other) issues as well (which contribute to the problem.

Now what?

Eeek! Are you using Jaunty? If so, maybe it’s a bug? See here: https://bugs.launchpad.net/ubuntu/+source/gconf2/+bug/328575

If so try this command in the alt+f2 “Run Application” instead: gnome-terminal -e "sudo -i"

(I’ve had to do reinstalls a few times now).

Anyway, I couldnt solve the problem by killing nautilus ( in fact i dont know if it was running .. ) so i ve reinstalled ubuntu ;(

alt+f2 is not a terminal, it’s a “Run application” applet. To open a terminal in Ubuntu Linux 8.04 access terminal via your Gnome menu like this:

Applications -> Accessories -> Terminal

As mentioned, alt+f2 is not a terminal, but you can access terminal after the alt+f2 combo by typing gnome-terminal in the available text field (that you’ll see when the “Run Application” applet opens up).

I hope this helps you. :)

I’d like to kill nautillus :/

Thanks :)

Hopefully this answer helps you. – Cheers!