Try a NEF file downloaded from a camera test site. May be your NEF is corrupted.
You may also trying to disable the use of the graphics processor for testing. (Properties)
Does turning off »Use Graphics Processor« in the Performance Preferences (Photoshop > Preferences > Performance > Graphic Processor Settings) and restarting Photoshop have any bearing on the issue?
Also Photoshop > Preferences > Camera Raw > Use Graphics Processor.
Make sure you have the latest video graphic driver installed from your manufacturer