I've been using Lightroom for 3 years. I usually have no problem editing between Lightroom and Photoshop, but yesterday a file crashed in Photoshop, as it was saving back to Lightroom. Now I cannot open files to edit in Photoshop. The error says "Lightroom was unable to prepare the selected file at /Volumes/2014 Photography Lightroom Back-Up/2014-08-22/DSC_1698.NEF for editing. It will not be opened." I have to get this sorted ASAP, anybody got any ideas?