i had somewhat the opposite problem: my site was showing up on yahoo's search with a weird title, something i've never had as my title and certainly not anywhere in my html.

i emailed them and they replied saying, "The title and description listed in the Yahoo! Search results can come from many different places, only one of which is the actual metadata in the page itself. The title and description can also come from descriptions on other websites which link to yours or directory services such as the Yahoo! Directory or other third party directory services."

i had to add "noodp, noydir" to the meta robots tag on my site to prevent this from happening.