I got a new PC laptop, retrieved all old HD contents from my external HD, installed LR 5.6 (5.4 on previous PC) and when I tried to open up my old Lightroom catalog it has an error saying "Lightroom has encountered problems reading this photo. You will not be able to make adjustments to this photo". I tried to open the catalog straight from my external HD with the same error message. I've read about four billion forum threads to try to figure it out- files do not seem to be missing as most threads indicate. The other threads suggest there is a corruption with the file, but I don't THINK that is the case. Are there any other suggestions? If the file is corrupted, how do I find out for sure? Have I lost all my edits??