how to remove “Blog Archive ” from page title?

I have edited my header.php file so that the code below is used for the title, instead of the default.

<title>
<?php if ( is_home() ) { ?><?php bloginfo('name'); ?> - <?php bloginfo('description'); ?>
<?php } else { ?><?php wp_title($sep = ''); ?> - <?php bloginfo('name'); ?>
<?php } ?>
</title>

BUT, my posts still have the default “site name >> Blog Archives >> post title” format! Does anyone have any idea where that can be coming from? For an example, see my site at GoRobotics.net.

I’m at a loss, I’d appreciate some help.