I just upgraded to the 4.4.3 version because of the new option to save tag and color class in a sidecar file.
I use Nikon Capture which removes that info in older versions.
But now when I open the NEF file in Photoshop (using the Nikon File Format loader) it says 'The embedded ICC profile cannot be used because of a program error. Ignoring the profile'.
This only occurs when I have color classed the file and resaving the NEF in capture does not fix it.
It would be good to know what version of Photoshop you are using, what version of the NEF File Format plugin you are using, what version of Nikon Capture you are using, and what OS you are running on.
If you have PM writing metadata to XMP sidecar files, then PM is not modifying your NEFs. Re-saving the NEF in Nikon Capture is unlikely to make any difference if it is the XMP sidecar file that is tripping up the NEF plugin. What happens if you remove/rename the XMP sidecar file? Does the plugin work again?
-Kirk