mac air 10.7.2 when i open 'system preferences / desktop and screen saver' i get the spinning beach ball and it never stops, with status: loading images. i had accidentally clicked on a folder inside iphoto containing hundreds of pictures, instead of my desktop images folder. now nothing in the window is clickable. can force quit out of it but the ball starts spinning again on re-entry as it attempts again to load images. tried restart and also safe start, ball spinning again on reentry to this syspref window. i've waited an hour. would like to terminate the attempt to load images so i can click the correct folder and be on my way. thanks for any help offered.