User’s login picture changing doesn't work.

Hi,

I recently purchased a MacBook Pro. I wanted to change my user’s login picture, but it crashed really bad. After a few tries it worked, but that was with a lot of effort, I had to restart my Macbook and force quit ''System Preferences''. Now I have the problem that I can't change it at all and it keeps getting stuck when I want to change the picture (see photo), restarting my Macbook doesn't work either.

How can I fix this?