Oh, I should probably have included that info. I'm on a macbook pro, with a built-in Intel graphics 4000 card. I'm really not a computer whiz at all, and since my first language isn't English I find it very exhausting to read long and complicated articles on the matter. I did, however, manage to find out that my graphics card needed to support something called OpenGL 3.0 (whatever that is), and my conclusion was that my card didn't support this, because I wasn't able to check the lighting&shadows box under preferences. But then, after updating firestorm to the newest version, I was suddenly able to do this, and a whole new world opened up to me! But now this happens, so I guess my graphics card cannot perform these kind of tasks afterall? I'm confused, because the tutorial you linked me to mentions mac, but goes on to explain about windows.
--Edit: If you guys think it's likely that the problem lies in my graphic card, then atleast I know where to go from now. I'll try to read up on this on apple's web pages, and see what I can find out. Again, thanks for the help!