Mobs Don't Move

[SicksonFSJoe]

After a while... I learned how to port forward my router to play with other people not in my LAN. I logged in using localhost and started playing around. I kind of wanted to do an SMP and a bunch of minigames in one pack, but there was one problem. Even when it was only me on the server.. the mobs just looked around. They could turn, they would still burn under sunlight, so they still had AI. Just none of them were moving of any sort. You could hit them, and kill them. When you hit chickens, they teleport. 

I believe this is kind of a problem.... and if anyone knows how to fix it.... I would be grateful. It's probably something ridiculously stupid....