Comment 2 for bug 575600

I found out what caused this -> it's an error in the "add-apt-repository" command.

Here is how to fix it:

sudo gedit /etc/apt/sources.list.d/docky-core-ppa-lucid.list

In this file you'll see two lines: one that starts with "deb...." and one with just a letter "n". Remove the line with just the letter "n" (I have no idea why the add-apt-repository adds that letter), save the file and then run:

sudo apt-get update

Now everything should be fine.