Hi Nikkoreye, Juerg,
Luckily I had only a small number of files affected and the {fbas} workaround was fine for the rest. Nikkoreye, I duplicated the problem with ViewNX2 and was able to see the original frame number with exiftool. exiftool calls it File Number. Try the following from a terminal window, having changed directory to the appropriate folder.
exiftool -a *.NEF | grep "File N"
This will print out a list of the 'File Name' and 'File Number' for each file.
It should be possible to write a script to automatically rename the files! -- any script experts out there?
I hope this is helpful
Regards
Martin