Sökte lite hos Apple: http://docs.info.apple.com/article.html?artnum=300242
iTunes 4.7 cannot sync photos to iPod Photo from a locked volume
When iTunes 4.7 first syncs photos to an iPod Photo, it creates a cache folder in the folder where the photos are stored.
If you don't have write access for the selected drive or volume, you will get a "permissions error" when you try to sync photos. This will happen because iTunes cannot create the cache folder on the read-only volume.
The solution is to copy the photos to your hard drive first, then tell iTunes where the photos are stored. Be sure not to select a volume that is always read only, such as a CD-ROM or DVD-ROM disc.