Don't you hate it when you're trying to solve a problem and you find old answers to problems that have since been solved for you? Well, almost solved --or more betterer solved than before.
http://www.4guysfromrolla.com/articles/111704-1.aspx presents problems with <%@ Page SmartNavigation="true" %> and gives Javascript examples with hidden fields. This was a version 1.0 problem, since deprecated.
Microsoft fixed it with Page.SetFocus and Page.MaintainScrollPositionOnPostBack. Still, trying to set the focus on a field within a templated control or within a named container requires you to either understand the control hierarchy, or use a recursion method that acts like a squirrel running up and down a tree and back and forth on each branch looking for his nuts.
Things get complicated when using a Master Page and children Pages --more later