Lightroom builds its own jpg file when you import the image, so if it shows corrupt in Lightroom then the actual raw file is corrupted. ViewNX would not. If you use the camera to view the file on the LCD screen, does it look ok there? That would be the jpg file embedded by the camera into the NEF file. You would also be viewing this when you see a thumbnail in a file folder. If the LCD or thumbnail looks ok, then that would rule out any sensor or camera processing problem ( except writing) since the camera builds this jpg before writing the file.