Hello,
in the file mod_cblogin.php, at line 709, you should add a space after class="cbLoginForm" or we can't validate our xHTML code, thank you.

Yes, I've downloaded it yesterday, but there was no space after cbLoginForm's class, so I've added it manually.
These are the original lines from mod_cblogin.php:

echo '<form action="'.$loginPost.'" method="post" id="' . $idFormLogin . '" class="cbLoginForm"';
echo 'style="margin:0px;">'."\n";