Andy, re the iPhoto library stored on a NAS, I had trouble with mine too when the library was set to link photos to their original folders. After changing to the option of importing a copy rather than linking (tick a box in the advanced prefs somewhere), I have not had any more problems (touch wood!). This is with around 8000 jpeg photos. The downside is that it takes double the storage space unless you are happy to go along with iPhotos filing in 'rolls'. Me, I prefer to keep shots from different cameras in their own separate folders.