Why am i all of a sudden having trouble dragging and dropping large groups of photos from iphoto anywhere

Question

This just started happening a few days ago- for some reason I am not able to highlight photos in iphoto and drag and drop them into a folder/ desktop. I can sometimes do one at a time, but not always. When I drag the group somewhere, I see the green + icon, and the red number of photos, but the photo icon doesn't get smaller, like it normally does when it's about to be moved. And once I let go to move it, nothing happens.

Answer 1

Try this:  launch iPhoto with the Option key held down and create a new, test library.  Import some photos and check to see if the same problem persists. If it does then try this basic troubleshooing fix: make a temporary, backup copy (if you don't already have a backup copy) of the library and try the following:
1 - delete the iPhoto preference file, com.apple.iPhoto.plist, that resides in your
     User/Home/Library/ Preferences folder.
2 - delete iPhoto's cache file, Cache.db, that is located in your
User/Home/Library/Caches/com.apple.iPhoto folder (Snow Leopard and Earlier).
or with Mt. Lion from the User/Library/Containers/com.apple.iPhoto/
Data/Library/Caches/com.apple.iPhoto folder
3 - launch iPhoto and try again.
NOTE: If you're moved your library from its default location in your Home/Pictures folder you will have to point iPhoto to its new location when you next open iPhoto by holding down the Option key when launching iPhoto.  You'll also have to reset the iPhoto's various preferences.
NOTE 2:  In Lion and Mountain Lion the Library folder is now invisible. To make it permanently visible enter the following in the Terminal application window: chflags nohidden ~/Library and hit the Enter button - 10.7: Un-hide the User Library folder.
OT