What software did you use to download the files from your camera? If it was an older version of Nikon Transfer, that could be the source of the problem.
You can correct the corruption from obsolete versions of Nikon software using a utility from here:
And you can avoid the issue for new NEFs by not using Nikon software with them.
Usually the problem is caused when you get a new camera and use the older Nikon software that came with a previous Nikon camera. It would be wise to uninstall this older software and either not install any Nikon software or only software that came with your newest Nikon camera.
Wow, well that's what I did. Thank you.
I removed all the Nikon software and re-uploaded the images through Bridge. WOW. Thank you! I'm not going to worry about the utility, because I've mostly been shooting in jpg since my old photoshop version couldn't process the NEF files. No loss, removing the Nikon software, and the image processing is so much better than my old CS3.
Thank you for the info. Much appreciated!