problem ONLY in IE8 ???

The application works perfectly in all browsers - except IE8.  Other versions of IE work just fine too.  To be specific, there are 2 panels that show or don't show depending on which buttons are clicked.
Therefore I assume, either correctly or incorrectly, that the code is correct, but needs to be altered to accomodate the uniqueness of IE8.
The panels are shown or hidden in the code behind, not the client side, using the visibility set to true or false.  There are two buttons on the bottom of the page that cause the problem:
<asp:button id="btnUpdate" OnClientClick="return ValidateUserSoap();" OnClick="btnUpdate_UserSOAP_Click" CssClass="button" runat="server" text="Update" /> &nbsp; <asp:button id="Button2" OnClientClick="ChangeHeader(false); return true;" OnClick="btnCancelClick" CssClass=& ...