Critical error in final stage of website launch - URLs are BROKEN!

Question

We developed the wordpress site here:

wwww.kirschfamilycomputerservices.com/sam/wheresthefairness

^^ URL does not exist now.

When the website was done, we transferred the database & theme over to a new host.

The issue is odd and really critical. We have to present the website to the client tonight, and none of our URLs are working properly.

the index to the new host is this: http://www.advertisingagency.me/wheresthefairness/

The links just under the header to the right are called in a list in the header PHP file and look like this:

<div id="wtfloginfb">
<?php
if ( is_user_logged_in() ) {
    echo 'Welcome Back!';
} else {
    echo 'Hello! New to WTF?!';
};
?>
 <?php wp_register( ' '  , ' ' , ' ' ); ?>/
<?php wp_loginout( home_url()  ); ?> |
<a href="<?php bloginfo('template_url'); ?>/new-case">State Your Case</a>| 
<a href="<?php bloginfo('template_url'); ?>/cases">View Cases</a>

</div>

The only file outside of the theme directory that I edited while designing the site was the general-template.php file, in which I changed the Site Admin link to display as "Dashboard" and made it point to root/dashboard.

So the problem is this.. When you go to the website and hover over a link, it shows the correct path to the file in question, however, when trying to navigate to ANY page directly, we are always given this error:

Not Found

The requested URL /sam/wheresthefairness/index.php was not found on this server.

So what do you guys think the problem could be? Could it be somewhere in the WP files themselves? Or does this sound like a database error? I've honestly never encountered something like this. I've never pointed my browser to a very specific path, and had it tell me that it couldn't load the page, because it tried to go to a different path...

1/19/11-4:36pm Edit to add: We get this error whenever we try to direct link to a post or a page. So essentially, the only pages we can actually view on the new host is the index page, and wp-admin.

Answer 1

Posting as an answer from the @OneTrickPony comment above:

1. Verify that mod_rewrite is enabled on your server.
2. Assuming that mod_rewrite is enabled, ensure that the root WordPress install directory is WordPress-writeable, or that, if it exists, the .htaccess file in the root WordPress install directory is WordPress-writeable. (See file permission scheme for WordPress, and Hardening WordPress: File Permissions.)
3. Then, in your WordPress admin area, go to Dashboard -> Settings -> Permalinks. Click "save" (no need to change settings), which will force a flush of the WordPress URL rewrite rules, and will rewrite the mod_rewrite rules to the .htaccess file.

Answer 2

As per comments functionality of pretty permalinks in WordPress has dependencies on server configuration. So it differs, depending on server used.

List of documented dependencies is available in Using Permalinks article in Codex.