I have to admit that I don't know what I've done here, but none of the buttons in my scene are registering click events.
I have a simple bar at the top of the scene with a back button on it. The button has a collider on it. It's on the NGUI layer and is being drawn properly. It has the UIButton script attached to it. The size of the collider is a bit larger than the button.
Anyways, I'm sure I'm just missing something simple... but appreciate any suggestions.