How is movement determined?

[IndyPendant]

Hrm. Maybe I need to clarify.

There are two, seemingly mutually exclusive, situations I am dealing with here:

1) In single-player games, I will move to attack an enemy province with an army, then end my turn. Next turn, I discover that the A.I. has sent a small force to harry my much larger army, and that battle seems to have negated my own movement order for my army. This doesn't always happen, but it does happen with annoying regularity.

2) In one of my MP games, I have been chasing an enemy army all over my own territories, and every time I move into a territory he has conquered, he moves out of it into another one of my territories, conquering *that* one. Once, we even exchanged places!

Now. From the responses to this post so far, it seems that if my army moves into a province an enemy army occupies, and *that* army at the same time attacks one of my provinces, then I will never, ever catch it. I have to anticipate its movement to catch that army.

But if that's the case, then scenario 1) in SP games is impossible. The AI army could not cut off my army's movement into its territory by attacking me, since our move orders would then resolve at the same time (because we are each moving into 'enemy' territory), and we would simply exchange places.

(And the AI's attacks do not involve stealth units, in case that's one theory--i.e. stealth in, then "Attack Current Province".)

Does the AI get special treatment this way? If so, that seems decidedly unfair for MP games...