Basically, all I did to existing Civ-specific units was change their technological requirements, stats, and icons.. What that I did could cause the game-crashing error? Just because they use the same icon as another unit in existance at the time? These aren't 'new' units -- just editing old ones. I thought that would make things stable -- guess I was wrong...
Thanks for helping me out!

:king: :egypt:

Hmm. Did you rename any of the units?

You're right, I did re-name them -- that must be the problem, then.
So where'd the conflict happening, in that case? What needs editing?
Thanks for your reply, BTW! :)

You need to create a folder for that unit with the exact name of the unit in the art\units section :D You also need to have a .ini file with the exact name of the unit that tells it what files to use.