Black spaces in Zoo Tycoon 2

I have installed the Extinct Animals expansion pack for ZT2 and now I get
black spaces in the landscape whenever I load the game. I have gone thru the
recommended fixes but nothing seems to help. If i click on the black space,
the correct landscape fills in, but if I save the game and then reload it,
the black spaces are back.

Any suggestions for what might be wrong and how to fix it?