single.php was OK, as in the original download.
everything before the sidebar call could be relevant; just checking, as this is not in the original download, it has to be something either through your edits or through added plugins.
you seem to have replaced the original section in header.php:
<?php if ( get_theme_mod( 'header_image' ) ) : ?>
<div id="header-image">
<img src="<?php header_image() ?>" width="950" height="200" alt="" />
</div>
<?php endif; ?>
with your <!-- Begin slideshow --> code, with one opening div
<div id="slideshow">
and two closing divs
</div>
</div>
your choice:
remove either line 62 or line 63 of your header.php pastebin code.