I have Lightroom 3 on a newer Windows 7 PC. Two internal hard drives. My Image files and lightroom catalogs are on the C drive. I would like to backup the lightroom catalog on the other internal drive "E". When I get to the catalog backup dialog, it only goves me option on the C drive - It doe snot navigate to "E" or any external drive. It forces me to backup on the C drive. I can nevigate to other drives everywhere else in Lightroom e.g. folders. Please help.