ASP.NET 2.0 webapplication

DropDown list and button on same page
DropDown_SelectedIndexChanged - redirect to selected item value
Button_Click - redirect to another location

Select item from dropdown correctly goes to selected location.
Back arrow returns to my page.
Selected item is shown as selected.
Selecting button transfers to previously selected item URL and not the URL
in the Button_Click handler.

How do I "reset" the DropDown to its original value (displaying item[0]) for
subsequent selections?  What was the source of you information?

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