Game crashes: questions and answers.

Question: How can the AI's use of spells and creature abilities affect game crashes? I've just created a mod that adds spells and modifies some abilities (and also slightly adjusted some stat points), but I've noticed that the AI sometimes moves creatures normally, while in other places (including random ones), it constantly crashes the game! Moreover, if you remove the unit that causes the crash, everything works fine, and the rest function normally.