The ajax login didn't work from the register page. I think this is because there are two input boxes with the same ID in this situation. Renamed the ajax login form's ID's to make them unique.

<div class="side-block">
<div class="side-block-title">
{% block block_title %}{% endblock %}
</div>
<div class="side-block-content">
{% block block_content %}{% endblock %}
</div>
</div>