I am trying to set up a mega menu and have followed the instructions here: https://www.nothingbutsharepoint.com/sites/eusp/pages/a-megamenu-for-sharepoint-2010-using-a-dvwp-and-a-list.aspx
When I add the DVWP to my master page I start getting access denied when trying to access most of the other sites / pages in the site collection. I had a similar issue before, when I moved <SharePoint:DelegateControl ControlID="SmallSearchInputBox" runat="Server"/> to a different div tag in the master page I didn't move the <asp:ContentPlaceHolder> tag with it and started getting access denied on site permission pages.
I am not moving or removing any code that is currently in the master page, simply pasting the DVWP underneath the <SharePoint:AspMenu> tag.
Any help would be greatly appreciated.