Loop Help

I have a website, thethoughtbubble.me
It’s currently under construction, but close to done.

I’m having issues with my categories links.

If I used the following HTML and PHP, my site breaks. The stick-it notes get all screwed up.

<?php get_header(); ?>
<?php include('nav.php'); ?>

<div id="mainContainer">
    	<div id="mainContentContainer" class="borderDefault">
		<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
            <div id="contentDate">
            Posted on <?php the_time('F jS, Y') ?>
        	</div>
            <div id="contentNavContainer">
	    	</div>
            <div id="contentTitle">
            <h1><?php the_title(); ?></h1>
            </div>
            <div id="content">
          	<p><?php the_content(__('(more...)')); ?></p>
		<?php endwhile; else: ?>
		<p><?php _e('Sorry, no posts matched your criteria.'); ?></p><?php endif; ?>
            </div>
        </div>

<?php get_sidebar(); ?>
<?php get_footer(); ?>

However, as soon as I remove any information pertaining to the loop and am left with:

<?php get_header(); ?>
<?php include('nav.php'); ?>

<div id="mainContainer">
    	<div id="mainContentContainer" class="borderDefault">
            <div id="contentDate">
            </div>
            <div id="contentNavContainer">
	    </div>
            <div id="contentTitle">
            <h1></h1>
            </div>
            <div id="content">
            </div>
        </div>

<?php get_sidebar(); ?>
<?php get_footer(); ?>

My site works fine.
Any thoughts? I don’t think it’s my HTML, as the other parts of the site are working. It’s only on when you click on a category.