Hello,
I saw on my log file I getting this error

2015-11-11T21:48:25+00:00 ERR (3):
exception ‘Mage_Core_Exception’ with message ‘Tipo blocco non valido: Mage_Megamenu_Block_List’ in /var/www/clients/client1/web1/web/app/Mage.php:595
Stack trace:
#0 /var/www/clients/client1/web1/web/app/code/core/Mage/Core/Model/Layout.php(495): Mage::throwException(‘Tipo blocco non…’)
#1 /var/www/clients/client1/web1/web/app/code/core/Mage/Core/Model/Layout.php(437): Mage_Core_Model_Layout->_getBlockInstance(‘megamenu/list’, Array)
#2 /var/www/clients/client1/web1/web/app/code/core/Mage/Core/Model/Layout.php(472): Mage_Core_Model_Layout->createBlock(‘megamenu/list’, ‘megamenu.list.t…’)
#3 /var/www/clients/client1/web1/web/app/code/core/Mage/Core/Model/Layout.php(239): Mage_Core_Model_Layout->addBlock(‘megamenu/list’, ‘megamenu.list.t…’)
#4 /var/www/clients/client1/web1/web/app/code/core/Mage/Core/Model/Layout.php(205): Mage_Core_Model_Layout->_generateBlock(Object(Mage_Core_Model_Layout_Element), Object(Mage_Core_Model_Layout_Element))
#5 /var/www/clients/client1/web1/web/app/code/core/Mage/Core/Model/Layout.php(210): Mage_Core_Model_Layout->generateBlocks(Object(Mage_Core_Model_Layout_Element))
#6 /var/www/clients/client1/web1/web/app/code/core/Mage/Core/Controller/Varien/Action.php(344): Mage_Core_Model_Layout->generateBlocks()
#7 /var/www/clients/client1/web1/web/app/code/core/Mage/Catalog/Helper/Product/View.php(73): Mage_Core_Controller_Varien_Action->generateLayoutBlocks()
#8 /var/www/clients/client1/web1/web/app/code/core/Mage/Catalog/Helper/Product/View.php(144): Mage_Catalog_Helper_Product_View->initProductLayout(Object(Mage_Catalog_Model_Product), Object(Mage_Catalog_ProductController))
#9 /var/www/clients/client1/web1/web/app/code/core/Mage/Catalog/controllers/ProductController.php(132): Mage_Catalog_Helper_Product_View->prepareAndRender(5979, Object(Mage_Catalog_ProductController), Object(Varien_Object))
#10 /var/www/clients/client1/web1/web/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Catalog_ProductController->viewAction()
#11 /var/www/clients/client1/web1/web/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(254): Mage_Core_Controller_Varien_Action->dispatch(‘view’)
#12 /var/www/clients/client1/web1/web/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#13 /var/www/clients/client1/web1/web/app/code/core/Mage/Core/Model/App.php(365): Mage_Core_Controller_Varien_Front->dispatch()
#14 /var/www/clients/client1/web1/web/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#15 /var/www/clients/client1/web1/web/index.php(83): Mage::run(”, ‘store’)
#16 {main}