I had the same problem and I had already formatted and reinstalled windows (not the entire drive, just my windows partition) so I was super confused. After reading the posts here (and still being the cautious person that I am) I isolated that nikon file in a folder called "Nikon NEF plugin isolated". For some reason this didn't work and I was Obsessed looking for another solution. After I deleted my isolation folder the problem went away.

BTW i'm using photoshop 7 on the computer in question

Thanks for your help

Bob