If you're on 5.5 there's something I'm just beginning to figure out, though maybe Jelisa would be able to give the real right or wrong of it. If you import something to your object library that was made elsewhere AND it contains a reference for an image based texture it appears to go looking for the reference to that texture and not find it. I've had this happen quite a few times now, and each time it was with object libraries that were picture based, for instance my whole XFrog tree library. It's not impossible to fix though. If you use export and import rather than copying the library into the presets folder with copy and paste it seems to cope better. Well, I hope it turns out to be the above problem which is fixable rather than the much more serious and unfixable thing that has afflicted 5.01 users as well as 5 when you get too big an obp library and the whole thing corrupts. Rayraz is right, those are final :(