In IE8, i was not be able to see the dynamic menu items when hovering over the menu created with <asp:menu>.
after googling, we found solution to this problem.
add the css class
and refer to the above cssclass in <DynamicMenuStyle> of <asp:Menu> like below.
<asp:Menu ID=”Menu1″ runat=”server”>
<DynamicMenuStyle CssClass=”adjustedZIndex” />
We can also have hotfix for this issue to view the web sites in compatabality view by installing the hotfix.
Check out this link for more information: http://code.msdn.microsoft.com/KB962351