Havoc

For some reason, if I put custom floors or terrains into the Terrain Graphics File, then Blades of Avernum crashes whenever I try to enter a scenario, whether it's the one I'm working on or someone else's. I haven't tampered with the permanant files, and the problem goes away when I remove the custom images. Does anyone have any idea what I'm doing wrong?

 

If it helps, I use a Mac.

True enough. I've been having a lot of trouble with custom terrain; and my dad tried replicating the example in the Appendicies. It had less of a result than my efforts did.