1 Error left before full validation

I keep getting one error left before my site will validate

I know that it refers to the about page (deleting the code results in the link to the about page being deleted).

This is the problematic code in the left column:

<li class="title">NAVIGATION</li>
<li><a href="<?php bloginfo('home'); ?>">Home</a>
<?php wp_list_pages('title_li='); ?></li>

With:
<?php wp_list_pages('title_li='); ?></li>
being the link to the about page.

I’m not too familiar with xhtml (apart from the basic tags) and I couldn’t get anything from google.

Any help would be great