Well, that narrows it down a bit.
I usually crash RTW right at the start by having something wrong with
an ancillary file.

I recommend restoring the original file and make sure it won't CTD then.
Once you have a working file, make a single change and see if that works.
You can waste a lot of time on this if you're not careful. It can be something like a letter not capitalized.

Also, if you've got the -show_err working, try hitting Alt-F4 before you start your campaign, when you're on the faction selection menu. That will close RTW and show a dialog with any errors the game found when parsing the files, but that weren't game-crashing.