I know the problems I'm going to detail may have been addressed earlier but maybe I can provide new insight, and also that this may not be the proper subforum but... oh, well enough it is!
Of course, I found that the full main belt asteroids *.ssc would lockup Celestia, as many of you have, so I opted for the abridged one and I found the gigantic asteroid bug. I went over the *.ssc and found what had been causing that: there was a "+" sign on the radius' scientific notation exponential where there should be a "-" sign. I edited it in MS word substituting all "+" instances but still I got at least 50 asteroids with ~900 km in diameter when the only one that should have those dimensions would be Ceres, with the next biggest, Vesta at ~500 km. So I think it's a problem with the scientific notation's exponential where there are a few "06" instances but substituting that for "07" yielded nothing.
I maintained the future and past approaches and the NEO *.ssc's, and in a bit of exploring that included going over the solar system browser and finding the asteroid designations repeated a number of times and going to one of the locations and finding asteroid meshes superimposed on one another, I came to the conclusion that whatever script the maker of those *.ssc's used was faulty, or misused, and repeated incessantly a number of asteroid numbers with slight variations for the future approaches *.ssc. The same bug can be found at the tail end of the full main belt asteroids *.ssc. covering most of the "Year LetterPair|Number" designations and on all of the potentially hazardous asteroids *.ssc.
I in the end trashed the past and future approaches and kept the NEO *.ssc as it didn't have these problems and it packaged the information on the trashed *.ssc's in a better way.
Mind you I have no problem with deleting a small number of entries from one file to avoid duplications but I think these problematic files either should be dropped as add-ons or heavily edited.