I used my Mac mini VGA adapter.......

I used my VGA Mac mini adapter but when I unplugged it, my screen stay in data show mode. I'll try in screen settings and it works but now when I want to used it, it starts in datashow mode, then appears a screen with all colors and finally it turns rigth. I REALLY NEED HELP, I GET SCARY EVERYTIME ALL THOSE COLOR APPEARS. (it seems like the screen is crazy)