after installed lion on mba 2010, I've changed the wallpaper by "desktop and screen saver". but during to select the different wallpaper several times, "desktop and screen saver" to be freeze (beach ball), so I need to force quit. then I try to start "system preferences" again. It's startup page is "desktop and screen saver" and it freezes (beach ball) everytime then need to force quit. don't know related to lion or not. any hint? thx.