The DataSourceID of ‘TopNavigationMenu’ must be the ID of a control of type IHierarchicalDataSource. A control with ID ‘topSiteMap’ could not be found.

No differences in web.config or errors in the ULS. After a few minutes with ProcessMonitor I noticed "Access Denied" errors for "Microsoft.SharePoint.ApplicationPages.dll" in the "_app_bin" folder.

I was not part of the installation of this SharePoint server and couldn´t tell if some special configuration had been done to cause this.

To solve this I gave "Everyone" Full Control on the file.