In order to investigate your case we would a bit more information. For example we would need the RadMultiPage, PageViews and Grids declaration. Both RadMenu items do have PostBack set to "false" so clicking on the RadMenu items does not perform post-back. Could you please explain how exactly show/hide grids?
In order to avoid sharing your project information and be able to attach a runnable sample project you can open a support ticket. In the forum threads you can only attach images.
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