No matter what size map I choose when I start new game, it generates a tiny world map...

I've played through several games on this machine with no problem (and several of the custom scenarios work just fine as well), but I can't seem to start a new game with anything but a tiny map. If I pick large, huge, etc, it always starts me on a tiny map.

This could be human error... but it's driving me mad! Thanks in advance for any help someone might have.