Sidebar dropped

Have you tried removing your widgets one-by-one to see if one of them is the culprit?

I notice one of them is trying to embed an AVI movie using the IMG tag. That may not be the problem, but it’s probably not going to be very effective, either.

on the main home page, you have one line double:

here is the section from the html code of the browser:

<div id="post-35" class="post-35 post type-post status-publish format-standard hentry category-mental-training category-training category-training-programmes">
			<div class="postdate">
<div class="month m-04">Apr</div>
<div class="day d-27">27</div>
<div class="year y-2011">2011</div>
</div>
<div class="commentbox">
<a href="https://intelligentrunning.com/?p=35#respond" title="Comment on How do you train between programs?">No Comments</a></div>
		<div id="post-35" class="post-35 post type-post status-publish format-standard hentry category-mental-training category-training category-training-programmes">

double-check the area in the template of your home page (or more likely in loop.php ?), where you have added the post date section and the commentbox.

in the source code, the double line is probably:
<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>

Many thanks. All sorted