Hi, my wife has a 4th generation 20" iMac (2.4 Ghz intel core 2 duo, 4Gb RAM) running Mountain Lion and for most of the time it runs well. However, when she uses iPhoto (latest version of iLife 11) for importing photos from her phone, etc, the iMac starts to slow down, then the spinning beach starts to appear, then the beach ball appears and won't go away. We have to switch off the iMac and then start again. I have reset the permissions once, and it seemed to be OK for a little while, but once it was used for more than 10 mins with iPhoto, the problem reappeared. Compared to my 27" i7 iMac, the fans on the 20" are on a lot. Any ideas please as this is becoming a nightmare, and the amount of use the 20" iMac gets doesn't warrant a replacement. Thanks in advance.