When I go to my Media Gallery there are 54 photos, if you can call them that, that are labeled Cache, that are black with a horizontal straight line that sometimes breaks into a few sections...like a graph. When I first open it says Last month. A couple of weeks ago, I deleted them all, one by one, but they have reappeared. What are these linked to? It seems as if they are taking up unnecessary memory, and are a pain to delete.