I was exploring my new fedora 19 after a crash in KDE (I don't know what I just did). I couldn't shutdown my laptop either with the graphical method or the terminal way (because the terminal refused to open). So I forced the shutdown by pressing the shutdown button in my laptop. After I restarted my laptop and entered my password and user, a black screen appeared and went back to logging screen again (the same thing happened with root).
So how should I fix this problem?