Pardon the funny title. I've created a little graphic demo of 200 balls bouncing and colliding, both against the walls and each other. You can see what I have currently here: http://www.exeneva.com/html5/multipleBallsBouncingAndColliding/

The problem is that whenever they collide with each other, they disappear. I'm not sure why. Can someone take a look and help me out?

UPDATE: Apparently the balls array has balls with coordinates of NaN. Below is the code where I push balls to the array. I'm not entirely sure how the coordinates are getting NaN.