I was facing a minor issue with an upgraded site from 2007 to 2010. Navigate Up button TOP level entry was pointing to a wrong entry. The screen shot below shows 2 masked entries. One entry was showing the right link, where the top level was pointing to the old 2007 site.
This is not the case, when you have issues with the whole Navigate Up button. For that you would remove “PlaceHolderTitleBreadcrumb” content place holder, this was much simpler than that.
To fix, Navigate to the Portal Site connection under Site Settings – Site Collection Administration (thanks to Samer – colleague who pointed me to the link). Change the settings on the page to “Do not connect to portal site”. That should take care of the issue. Simple step but handy solution.