Magento – Newsletter block at footer weird problem

In app/design/frontend/theme/theme/layout/newsletter.xml change from:

<reference name="footer">
    <block type="newsletter/subscribe" name="footer.newsletter" as="newsletter" before="footer_store_language" template="newsletter/subscribe.phtml"/>
</reference>

To:

<reference name="left">
    <block type="newsletter/subscribe" name="left.newsletter" template="newsletter/subscribe.phtml" before="-" />
</reference>

Take a look at Magento Newsletter form not working

Try

{{block type="newsletter/subscribe" template="newsletter/subscribe.phtml"}}

The form need to be posted to newsletter/subscriber/new which is define in

Mage_Newsletter_Block_Subscribe

/**
 * Retrieve form action url and set "secure" param to avoid confirm
 * message when we submit form from secure page to unsecure
 *
 * @return string
 */
public function getFormActionUrl()
{
    return $this->getUrl('newsletter/subscriber/new', array('_secure' => true));
}