I have an HP Photosmart 7520 and it always wants to print pdf-files on photo paper. It draws in the photo drawer and complains that there's no photo paper loaded. Why won't it print pdf-files on white office paper? What settings should I change? It works fine with word and excel files, and I do understand that it recognizes pdf-files as "photos" (I do print photos in pdf on that printer), but what if it's a document that I need on paper? Any ideas?