Our Intranet site has a custom site map provider - which is used across all site collections to consistently display the same navigation regardless of where the user is on the site.
Description of problem
A custom site map provider is used in the custom master page across the entire site collection. This site map provider is used to ensure consistent site architecture for the top navigation bar
Add the custom site map provider to all web applications' web.config files (except the web.config for Central Admin, and SharePoint web services). If thecustom site map provider is an XML based provider, ensure the .sitemap file is also uploaded to the appropriate location on the server (in our case, it's under 14\TEMPLATE\LAYOUTS\customername\customerTopNav.sitemap)