Few days ago, I solved a bug “Cannot rewrite post/page title” of Platinum SEO Pack plugin. If you search somewhere in the Net, you will see the main reason is miss wp_head() function in your WP theme but in my case, the reason is query_posts(). The developer used query_posts() function without wp_reset_query() after so $post variable will be overrided in somewhere if has post/page queries.
So, to solve this bug, just simple (always) put wp_reset_query() after query_posts() except you want to reuse global $post variable.