James,
Excellent!
Here is what happened. There is more than one instance of Search installed. Apparently the Search package does not support multiple package instances, but allows them in error.
The Search package is already installed, but not mounted to a URL.
To fix this find your search package in the site map. Point your mouse at the link to "Set Parameters" or "Set Permissions" for the package and note the package_id of this from the URL of the link to unmount the package. You will need it in a minute. Unmount the package instance.
Next go to the Unmouted Applications link below the site map.
You have to delete one of the search package instances. By examing the URLs of the [delete] links, find the package_id of the search package you just unmounted and delete it.
Now go back to the site-map. You should have a directory with no packages mounted to it where Search used to be. Click mount and choose the one remaining Search package instance to mount there.
