This error only applies to players with a saved game from B17 that has a Classic Player in the game. The game will fail to load with the above message. I have made the adjustment to the DLL.
You only need this fix if you have a B17 save with a Classic Player and now have Build 18:
https://killerbeesoftware.com/edce/code/source_code/EDIEAI_B18HotFix.zip