This is a problem that happens to me, as well, Crab. If Jazz 2 always crashes whenever you try to ban someone, the fault usually lies with a deleted file. Check your Jazz 2 folder to make sure these two files are there:

1. banlist.lst
2. banlist.txt

If they aren't there, just make a new file with that name. You don't have to put anything in there. Blank is fine. Note that it is LST in the first file, not 1ST.

Edit: Ignore people who call you a n00b. First off, it isn't an insult. It's just a way of players insulting others to make themselves feel better about their own abilities. Don't fight back. A reaction is really what they want.