Redirect Problem – htaccess?

Hi, hope this post is in the right place…

We use two registration links allowing users to register for different roles:
/wp-login.php?action=register&utype=subscriber
/wp-login.php?action=register&utype=contributer

The subscriber link is the simple registration page and the contributer link contains extra fields. When a registration page fails (e-mail already in use) it is redirected to just the standard /wp-login.php?action=register page. How can I direct to the page that the request came from i.e. subscriber if that’s the page that the request from, or contributer if it came from that link?

I’ve tried:

function my_reg_fail($username){
// Get the reffering page, where did the post submission come from?
$referrer = $_SERVER['HTTP_REFERER'];
    // if there's a valid referrer
    if(!empty($referrer)){
        // redirect
        wp_redirect($referrer);
    exit;
    }
}

This seems to cause a problem, in IE it does nothing and in Firefox it says:

“The page isn’t redirecting properly Firefox has detected that the server is redirecting the request for this address in a way that will never complete.
This problem can sometimes be caused by disabling or refusing to accept cookies.”

The $referrer returns the correct address if I echo it, I think it’s something to do with htaccess?

The htaccess file contains:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /proofing/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /proofing/index.php [L]
</IfModule>
# END WordPress

Where ‘proofing’ is the directory of the WordPress site. Any thoughts on this?

Many thanks!