apm_package_id_from_key is the problem here, I do believe.
packages/news/www/index.tcl makes this call:
set search_url [news_util_get_url search]
news_util_get_url in turn makes this call:
set package_id [apm_package_id_from_key $package_key]
Now, apm_package_id_from_key returns an error if it is called with "search" as package_key AND more than one instance of the Search package are mounted. (Possibly also if the Search package is installed but not mounted, but I'm not sure).
Did you mount several instances of search?
In either case I'm afraid I'm not sure what to do about this, but perhaps replacing [apm_package_id_from_key $package_key] with [site_node_closest_ancestor_package $package_key] (in proc: news_util_get_url in the file: packages/news/tcl/news-procs.tcl) will help.
Let us know how it goes.