classifieds affecting author search

On this site:, we have the classifieds pligin installed.

If you click on an authors name, instead of bringing up all by that author, you get this result:

Classifieds By: Christopher Tobutt
Not Found

Apologies, but no results were found for the requested classifieds. Perhaps searching will help find a related classified.

why is the author search getting mingled in with a classifieds search and how do I change that? The user type is "author" for each author.