I click media, then pictures, all pictures and I get the last six photos coming up that I took. They are small thumbnails and I can make out the photos. When I select one and click delete, it says,"The selected file is read only. Are you sure you wish to delete the file?" I select yes and it doesn't delete. The thumbnail is still there, and if I select it to view it, there is a black screen with a sun and hill icon. I can still see the thumbnail. These "read only files are building up, how can I fully delete them?