It worked perfect for 40000 photos till yet. I started the iMac again several times but no way. The iPhoto starts but then doesn't proceed.
iPhoto '11
Posted on Feb 3, 2013 4:00 AM
Q: iPhoto stopped working on my iMac this morning after downloading some pictures from an SD card ( from canon EOS 1000D)
Maybe this will help
http://support.apple.com/kb/HT2638
What does "stopped working" mean?