I imported photos to Lightroom 3 from a 16GB SD card..about 500 of them. I have since removed the card, seemingly standard procedure, and now when I try to access/edit the photos from within LR 3 - it says, "The file named 'P1000319.JPG' is offline or missing." What do I need to do to reconcile this? I am under the impression that once imported, the photos are saved within LR3? Am I mistaken?