Ok, I've figured it out. This is where the read/write options for /data/Proto/Critters and /data/Proto/Items needs to be set to Read Only before starting the game, every time.
I'm sure you've found some help on the web to get you to that point, so hopefully this will make sense to you. Instead of changing the 'Mode' value from 0 to 4 in ddraw.ini open up the f2_res.ini file and change GRAPHICS_MODE from 0 to 2. This got the game running for me.
One problem I've...