After a total re-install, I'm going to try different combinations of settings to see which one induces the same freeze as before. I've left all mod settings and map parameters as default, generated a Diverse (Garden of Gaia) world with 100 year history, and created a Human Hero with no skills or attributes. She spawned in without a hitch.
I'm going to tweak settings one-by-one to see which induces the same freeze as before.
Here's my science:
Control: All settings as detailed above.
Spawn successful.Control +100 Random Creatures: Same control, only with 100 randomly generated creatures. One semimegabeast; no extra civs.
Spawn successful. Control +200 Random Creatures: Same as control, only with 200 randomly generated creatures. One semimegabeast; one extra civ which survived worldgen.
Spawn successful.Control +Item Types: Same as control, only switching on the extra trees, plant types, instruments, and toys as well as switching off simple toys and gemshapes. No random creatures this time.
Freezing occurs.Control +Extra Tree & Plant Types: This time I'm switching everything back to default except Tree & Plants, which I've switched on.
Freezing occurs. Getting warmer.
Control +Extra Tree Types: Switched off extra plants, just to see which one screws stuff up.
Spawn successful.Control +Extra Plant Types: Switched off extra trees and on extra plants.
Freezing occurs. (I finished my drink just in case it needed more time than usual. But nope. Freeze.)
I hope that helps. I'll try more combinations of things if you want. I've got a free weekend