Have just encountered this problem over the last few weeks.
I was unable to import into LR 5 or to convert to DNG with Adobe converter.
I have D800Es x3 and ceased using the CF cards hoping this may be the answer but still occurred affecting the first 7 images on card.
I have downloaded direct from cards to iMac using card slot - no external card reader
After reading the posts I tried some experiments.
It appeared impossible to open these images with Photoshop from desktop or from within Bridge. or to import into LR 5
The images opened in Capture One without a problem.
I made a few adjustments in C1 and saved as NEF - this file would not open in PS
Saved as tiff and the tiff file opened in PS CC no problem.
Perhaps someone from Adobe will read this & do something about it.
I imagine I am like many photographers who were dismayed by Adobe's new policies. I have been using LR 5 and fairly happily, but if I have to go through this rigmarole every time the fault occurs then my choice is simple as I can still use PS 6 on the few occasions C1 does not suffice.