ASP.NET 4.0 Rendering problems with the menu control after removing of controlRenderingCompatibilityVersion="3.5"
If you remove the controlRenderingCompatibilityVersion attribute from web.config the default mode for menu rendering changes implicitely from Table to List. If you still want to have your menu rendered with table tags you need to specify this explicitely in your asp:menu control by adding the RenderingMode attribute:
<asp:Menu runat="server" RenderingMode="Table" ... > ...</asp:Menu>(s. also the remarks section here in MSDN: http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.menu.renderingmode.aspx)
I had issues where a published menu rendered oddly. Adding RenderingMode="List" to the menu markup resolved my issues.
<asp:Menu runat="server" RenderingMode="List" ... > ...</asp:Menu>