That's quite fascinating. The game is hanging during "Writing Table", but I know that there is no error handling during the writing procedure. After writing the table it should immediately ask for "Continue?".
Also I have no explanation for the green background color. I remember that I entered a highscore on my Minimig a few days ago and now I tested it with UAE and had no problem either.
Will test it on my A4000 this evening. What are the specs of your 4000? 030, 040, 060? Any special hardware? HD floppy drive?
Would be interesting to hear about the experience with the highscore table from other players...