jos-Error: Unable to load renderer class

JSite -> dispatch() @ /home/rmccm13/public_html/index.php:42
JComponentHelper :: renderComponent() @ /home/rmccm13/public_html/includes/application.php:194
JComponentHelper :: executeComponent() @ /home/rmccm13/public_html/libraries/joomla/application/component/helper.php:348
require_once() @ /home/rmccm13/public_html/libraries/joomla/application/component/helper.php:380
JController -> execute() @ /home/rmccm13/public_html/components/com_content/content.php:16
ContentController -> display() @ /home/rmccm13/public_html/libraries/joomla/application/component/controller.php:761
JController -> display() @ /home/rmccm13/public_html/components/com_content/controller.php:74
JController -> getView() @ /home/rmccm13/public_html/libraries/joomla/application/component/controller.php:677
JError :: raiseError() @ /home/rmccm13/public_html/libraries/joomla/application/component/controller.php:903
JError :: raise() @ /home/rmccm13/public_html/libraries/joomla/error/error.php:251
JError :: throwError() @ /home/rmccm13/public_html/libraries/joomla/error/error.php:176
call_user_func_array() @ /home/rmccm13/public_html/libraries/joomla/error/error.php:214
JError :: handleCallback()
call_user_func() @ /home/rmccm13/public_html/libraries/joomla/error/error.php:765
plgSystemRedirect :: handleError()
JError :: customErrorPage() @ /home/rmccm13/public_html/plugins/system/redirect/redirect.php:109
JDocumentError -> render() @ /home/rmccm13/public_html/libraries/joomla/error/error.php:804
JDocumentError -> _loadTemplate() @ /home/rmccm13/public_html/libraries/joomla/document/error/error.php:107
require_once() @ /home/rmccm13/public_html/libraries/joomla/document/error/error.php:135
Gantry -> displayModules() @ /home/rmccm13/public_html/templates/rt_leviathan/error.php:41
GantryModulesRenderer :: display() @ /home/rmccm13/public_html/libraries/gantry/core/gantry.class.php:867
GantryFeatureDropdownMenu -> render() @ /home/rmccm13/public_html/libraries/gantry/core/renderers/gantrymodulesrenderer.class.php:65
JDocument -> loadRenderer() @ /home/rmccm13/public_html/templates/rt_leviathan/features/dropdownmenu.php:50
JError :: raiseError() @ /home/rmccm13/public_html/libraries/joomla/document/document.php:926
JError :: raise() @ /home/rmccm13/public_html/libraries/joomla/error/error.php:251