I've just installed tightVNC on my raspberry pi. After I rebooted the device, it showed the login screen, which usually doesn't appear. When I enter the login, there's a black screen with a blinking underscore for about three seconds, after that it returns to the login screen. The login is definitely not wrong, if I type in a wrong password it shows an error message.
So I booted to the command line and removed tightvncserver. Still, I can't login. If the raspberry doesn't boot to the GUI I can easily login with user pi, but with the GUI login screen the same doesn't work. How can I fix this?