Problem: live chat widget does not show up.

Reason: Live chat widget was added to footer template, but not through regular layout.xml, but widget.xml

Exception log shows:

#0 /home/user1/public_html/app/code/core/Mage/Core/Model/Layout.php(495): Mage::throwException('Invalid block t...')
#1 /home/user1/public_html/app/code/core/Mage/Core/Model/Layout.php(437): Mage_Core_Model_Layout-
>_getBlockInstance('chatbox/chatbox', Array)
#2 /home/user1/public_html/app/code/core/Mage/Core/Model/Layout.php(472): Mage_Core_Model_Layout-
>createBlock('chatbox/chatbox', '48958d0b714472a...')

Solution: The footer block cannot load widget block properly, hence hole punch for public footer block needs to be disabled.