stdClass::set_prefix() Error

Hi all,

Im trying to display some content from wordpress outside its folder using the following code:

<?php
ini_set('display_errors',1);
error_reporting(E_ALL|E_STRICT);
  // Include WordPress
  define('WP_USE_THEMES', false);
  require('./guides/wp-blog-header.php');
  query_posts('showposts=1');
?>
<div id="content" class="guides">
	<div id="contentLeft">
 <?php while (have_posts()): the_post(); ?>
<h2><?php the_title(); ?></h2>
<?php the_excerpt(); ?>
<p><a href="<?php the_permalink(); ?>">Read more...</a></p>
<?php endwhile; ?>

Trouble is when loading the page I get the following error:

Fatal error: Call to undefined method stdClass::set_prefix() in /html/guides/wp-settings.php on line 268

I have been able to isolate the cause of this problem which is my roots htaccess file which looks like:

Options -Indexes
AddHandler php5-script .php

RewriteEngine on

#RewriteBase /ssa

RewriteCond %{REQUEST_FILENAME}       !-d
RewriteCond %{REQUEST_FILENAME}       !-f
RewriteRule ^(.*)$   index.php?uri=$1 [NS,L,PT,QSA]

Now im not very familiar with htaccess but I dont understand why its breaking displaying wp content outside its folder?

Can anyone provide me a solution to get this to work? Thanks