Single posts incorrectly alligned in IE

My site loads correctly in Fire Fox, but clicking on a permalink in Internet Explorer 6.0 causes the page alignment to skew left.

Everything is XHTML valid, but try as I might I can’t figure out a fix. Anybody able to help?

My Single Post looks like:

<?php get_header(); ?>
<div id=”wrapper”>
<div id=”container” class=”<?php veryplaintxt_singlepagelayout() ?>”>
<div id=”content”>

<?php if (have_posts()) : while (have_posts()) : the_post(); ?>

<div class=”navigation”>
<div class=”alignleft”><?php previous_post_link(‘« %link’) ?></div>
<div class=”alignright”><?php next_post_link(‘%link »’) ?></div>
</div><!– END NAVIGATION –>

<div id=”post-<?php the_ID(); ?>” class=”post”>
<h2 class=”post-title”><?php the_title(); ?></h2>
<div class=”post-entry”>
<?php the_content(‘<span class=”more”>(Continued)</span>’); ?>
<?php link_pages(‘<p style=”font-weight:bold;”>Pages: ‘, ‘</p>’, ‘number’); ?>
</div><!– END POST-ENTRY –>
<!– <?php trackback_rdf(); ?> –>
<div class=”post-metadata”>

<?php if ((‘open’ == $post-> comment_status) && (‘open’ == $post->ping_status)) { ?>Post a comment or leave a ” title=”Trackback URI” rel=”trackback”>trackback.
<?php } elseif (!(‘open’ == $post-> comment_status) && (‘open’ == $post->ping_status)) { ?>Comments are closed, but you can leave a ” title=”Trackback URI” rel=”trackback”>trackback.
<?php } elseif ((‘open’ == $post-> comment_status) && !(‘open’ == $post->ping_status)) { ?>Skip to the end and leave a response. Trackbacks are closed.
<?php } elseif (!(‘open’ == $post-> comment_status) && !(‘open’ == $post->ping_status)) { ?>Apologies. Comments and trackbacks are both currently closed.
<?php } edit_post_link(); ?>
</h3>
</div><!– END POSTMETADATA –>
<?php comments_template(); ?>
</div><!– END POST –>

<?php endwhile; else: ?>
<?php /* INCLUDE FOR ERROR TEXT */ include (TEMPLATEPATH . ‘/errortext.php’); ?>
<?php endif; ?>

</div><!– END CONTENT –>
</div><!– END CONTAINER –>

<?php
global $veryplaintxt;
if ($veryplaintxt->option[‘singlepagelayout’] == ‘narrowcolumn’) { /* THEME OPTION FOR DISPLAYING SIDEBAR */
get_sidebar();
}
?>
</div>
</div><!– END WRAPPER –>

The relevant CSS:

div#wrapper {
width: 80%;
margin: 3em auto 0 auto;
}

div#container {

width: 100%;

}