I have an external drive that I keep most of my photos on.  I have a particular folder on the external drive I want to access.  When I click on that folder it opens, but instead of thumbnails of each photo, all the photos have the photo gallery icon instead.  Then when I click one of those icons, I get this message "Photo Gallery can't open this photo because you do not have permission to access the file location."  How do I change this so I can get my photos?  I have windows 8.