OK, this is weird. I installed iTunes 9 yesterday and since then the applications just randomly (Preview, Word, Pages, Textedit, Opera...) won't start anymore when I wan't to open some file (like Word file). I can only use Safari and iTunes. The only way I can make them work again is rebooting macbook. I can play with apps after that for 3 hours or so and then they won't open again. The icons just jump in the dock. I have also another problem: when I adjust sound or brightness then the bars in the icon move very slowly, not smoothly. This also occurs when I hold a backspace button down to delete text. I noticed this 2 weeks ago.