>I just stepped through the code. If I change the Age, the breakpoint stops the code showing me that sender is the date control, not the age control. It then runs through the method and changes the age based on the date, then it runs through it with the age control as the sender.

Well, sounds like your answer is the event is firing when you are not expecting it to fire. Is your value is getting changed as you expect, but then getting changed back?. Might want to look up what triggers the Text Changed to fire. Is there another event you could use to re-compute the value?
Tim