You have a hardware malfunction somewhere. It could be camera card, transfer hardware, hard disk or memory. You have to run diagnostics on the hard drive and memory. You have to be 100% sure it isn't the transfer hardware or camera card.
Thanks. Is it safe to rule out the camera card and card reader since my original downloaded file is fine? Since it's the copy from that file that becomes corrupted, not the original, that would mean it's not the card or the card reader, correct?
I don't know how to run diagnostics. Is there somewhere you can point me to find more info about how to do that?
Thanks so much.
I don't think it is safe to assume the card reader and camera card is fine. When you open the file in Photoshop, also open it in ACR to make sure that the corruption doesn't appear there.
I don't really have advice on exactly which diagnostics to run on your hard disk and memory. When I need to do so, I go to my favorite search engine.