I have been using <include /> elements in my xml comments in order to refer to common documentation. If the xml fragment from the external xml file contains references to namespaces that are not included in the original class, ReSharper considers that the namespace is not being used. If a code cleanup is then performed and the namespace is removed from the class, the compiler fails because the documentation references are no longer valid.

In the attached project, do a compile and everything is fine. Do a full code cleanup then recompile and the compiler will find errors.