By the way, does this bastard of a file keep re-creating itself, so that you constantly have to delete it...or does it stay gone?
EDIT: OK, now I am pissed!! I scored 39,250 and no goddam score.
Before playing, I deleted the bastard nv file. No good, my score still don't count!
Yes, you have to delete the file every time before play - it gets created whenever you play (whether you get a high score or not) and exit the game - so is it possible you deleted it, played a game and quit back to the c4a menu, then started Dig Dug again and got a high score (which would not then be recorded because the scores would go to the nv file preventing them being picked up by c4a on exit)?
I deleted the digdug.nv file after I encountered the problem, and it registered my score. Did that a few times now, worked each time. (EDIT: Just played a quick game to test, and it registered my 26k score ok)
Maybe it's possible you reached a high score, then played another round of dig dug to get a better score in that session? That could present a problem - maybe the .nv file is created when you enter the high score table first time, so if you have recorded a high score in the game you just played, then if you want to try for a higher score straight away you actually need to exit c4aMame, delete the .nv file and go back in again otherwise only the first score (or none) will be picked up by c4a.
If you feel you're not on course for a high score you'll be happy with, don't let it go so far as ending the game and entering your initials - reset the game (F3) and play again. Don't enter the high score table and play again immediately, might be a way of avoiding not registering?