In other words, you are experincing something like this
1) You start osu!
2) You see the main menu....a little bit of it until...
3) The screen goes dark and black and you are unable to see anything.
Am I correct?
If so, you may be lacking something in your video codecs or something like that. Or perhaps you are running a really old computer. I can't say for sure whats wrong with your osu! (because I did not experience anything like that), but I hope your troubles will be solved. But my most strongest guess is you running a computer which cannot fully support osu, or you are missing an important program or application to fully operate the program.