on one of my favorite cooking shows ("Good Eats") I heard that the secret to keeping a tall, thick cheesecake was to turn off the oven, but leave the cake in the oven (don't take it out). supposedly the dramatic decrease in temp from the oven to the outside air is what kills the cake, and if you leave it in the oven, its temp drops gradually.
Not speaking from experience, but just telling you what I heard. Post back here and let us know if it helps!
-- droxford