To see what's really going wrong here, we'll need to get some console output. So go ahead and open it up. It's in KMenu -> System -> Konsole
(or just press Alt-F2 to open the "Run command" dialog and type in konsole)
in there do this (and post back the output)
Code:
sudo apt-get install amarok
you'll need to enter your password to do that, and don't worry if you don't see what you are typing in, that's normal.
It will probably end in a error, so make sure you copy the whole thing here.
Also, can you post the contents of the file? "/etc/apt/sources.list" here (it contains the list of sources you're using)