Site Emergency – Is justhost a scam or WordPress consuming 100% CPU power

I am hosting my website (with few thousand visitors/day) with justhost (with dedicated IP); the website runs WP 3.0 with it’s own wordpress directory (eg: site.com/wpdir)

Justhost emailed me today saying that index.php file of WP is using 100% CPU on their shared hosting and suspended our accounts without any prior notifications.

There is nothing special codes in the index.php file of site (listed here) but why is it consuming such large power on justhost. Is justhost a scam? they don’t say anything about it.

Urgent help need.

<?php
/**
 * Front to the WordPress application. This file doesn't do anything, but loads
 * wp-blog-header.php which does and tells WordPress to load the theme.
 *
 * @package WordPress
 */

/**
 * Tells WordPress to load the WordPress theme and output it.
 *
 * @var bool
 */
define('WP_USE_THEMES', true);

/** Loads the WordPress Environment and Template */
require('./wpdir/wp-blog-header.php');
?>