There are several times when you should fold AA preflop. In those instances, which are very few, it can be the difference from getting paid and getting nothing at all. In cash games, I will NEVER fold AA preflop. Early in tournaments, I will NEVER fold AA preflop. If I am short stacked at any point of a tournament, I will NEVER fold AA preflop. I will fold AA preflop if....

I am assured to be in the money and a big stack goes all in preflop and gets 2 people to call. After this hand, I will definently be in the money. I fold, show my hand, and I'll catch up later (hopefully). If I'm in a satellite and guaranteed to get paid, I'm folding AA to any bigger hand than mine (this is the final stage of the tournament though). If I can take out an opponent who has a very few chips left, then obviously I'm calling. If there are 10 satellite tickets and only 12 people are paid, and I'm in 4th, and the #1 guy goes all in with 2 caller, I will probably fold. No reason to waste that much time without getting something.