What is "has wd my book world"????
And you can try rebuilding your iPhoto library
Quit iPhoto, if it’s open.
Hold down the Command and Option keys as you click the iPhoto icon.
The “Rebuild Photo Library” dialog appears.
Select the repair iPhoto library database, and examine and repair iPhoto Library file permissions” checkbox.
Thank you for your advice, but it didn't work... After that I rebuilded my iPhoto library, I have tried to copy the library to the Network-attached storage (NAS) Western Digital My Book World, but it didn't worked... I have the same message: The operation can’t be completed because one or more required items can’t be found. (Error code -43) !!!