Sorry for leading this completely into the wrong direction:
I delete my db3 files usually once every three or four months when my barebone gets noticeably slow. I had never problems with doing this.
Suddenly I have frequent crashes after the last update to to v6.32 build 1879. Quade suggested to delete the mentioned db3 files because the database could have been corrupted. I did this. Now they are completely new from scratch, but crashes happened after doing this.
Conclusion: The crashes have nothing to do with corrupted db3 files or Newsbin rebuilding them because they are missing.
I use Newsbin in a very passive way: 100% usage of autoload folders and Newsbin does the downloading, autopar, unrar. The the only real "usage" is sorting the download queue.
My Usenet computer is a very old VIA CPU barebone which is very silent and runs 24/7. I'm certain Win7 will not perform on this machine and I don't want to change a running system.