Updated note to users of the Nikon RAW Codec for Windows: Microsoft has received reports of compatibility issues with Nikon NEF files after installing version 1.0 of Nikon’s RAW codec posted in January 2007. Tagging the RAW files through Windows Vista or the Microsoft Photo Info tool after the codec is installed appears to cause these files to become unreadable in other applications, such as Adobe Photoshop. We have confirmed that these files can still be opened with Nikon Capture.
Nikon and Microsoft have investigated the issue, and have determined that no data is lost, nor is the image file damaged in any way. Nikon is working on an updated codec that will resolve this issue, and expects to have it released in the very near future.
Tagging the file using Photo Info without the Nikon NEF codec installed appears to be safe.