While running maintenance DiskWarrior found 5 files with damaged resource forks that could not be repaired. These were .psd files which appear to function normally. I don't know anything deep about Photoshop file format nor, for that matter, about Mac file formats in general. I assume the thing to do is open the damaged files in Photoshop and save each as a copy. Or is this even necessary? I had been using them unawares, with no problems.