Windows Explorer remembers the settings (position, size, column positions, and so on) for every folder you open by storing it under the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\Windows\ShellNoRoam
HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell
HKEY_CURRENT_USER\Software\Classes\Local Settings\Software\Microsoft\Windows\Shell
Nirsoft LastActivityView uses the above registry keys to add the View Folder in Explorer event. If you delete the subkeys under the above registry keys (With RegEdit), Windows will "forget" the settings of all folders.
Actually the bread crumb is showing you exactly where you are.
In Windows 7, the "Library" concept was introduced, which is like a folder for your folders or a meta-folder if you will. You can add folders from all over your PC and across networks to a library so that you can easily access all the contents through one click.
Your Documents library contains the traditional My Documents and most likely a folder called Public Documents (though I have seen one build of Windows 7 without Public Documents). By default, the My Documents folder is set as the save location. Which basically means when creating in, saving to, or copying to the Documents library, the file will be saved in the My Documents folder.
You'll notice you can expand the Documents library in Windows Explorer by clicking on the arrow to its left. There it will list the actual folders in the library. The one you are concerned with, if I am not mistaken, is My Documents.
So when you click on Documents you are actually seeing the contents of all the folders in the Documents library, which for you is most likely My Documents and Public Documents. But Public Documents is probably empty.
If you really want to see the bread crumb for My Documents you need to access My Documents directly and not through the Documents library.
Now about Search Results. I am not quite how would a bread crumb could even work here. Search Results don't really exist anywhere (well they do but I don't see the point of accessing them via bread crumb). Search Results were created then and there when you performed a search, so you are kind of at the root of the trail.
Best Answer
I did some Google searching and ran across this article that might be the answer to your question:
It's basically a walkthrough of the features in the new address bar in Vista. Windows 7 probably has the same behavior (will verify at home, we're XP at work). What's nice is that it's from the perspective of someone who has been using XP. About three quarters of the way in, the writer mentions that if you use access the history using the far right triangle (next to refresh), it will give you full folder paths.
This is a screenshot of what using that triangle should look like. If I'm reading your question correctly, this is what you want: