有时Magento停止工作，当我检查var / report /得到这个：
a:5:{i:0;s:59:"Mage registry key "_singleton/core/resource" already exists";i:1;s:868:"#0 /home/siteName/public_html/app/Mage.php(223): Mage::throwException('Mage registry k...')
#1 /home/siteName/public_html/app/Mage.php(477): Mage::register('_singleton/core...', Object(Mage_Core_Model_Resource))
#2 /home/siteName/public_html/app/code/core/Mage/Core/Model/Resource/Setup.php(141): Mage::getSingleton('core/resource')
#3 /home/siteName/public_html/app/code/core/Mage/Core/Model/Resource/Setup.php(234): Mage_Core_Model_Resource_Setup->__construct('core_setup')
#4 /home/siteName/public_html/app/code/core/Mage/Core/Model/App.php(417): Mage_Core_Model_Resource_Setup::applyAllUpdates()
#5 /home/siteName/public_html/app/code/core/Mage/Core/Model/App.php(343): Mage_Core_Model_App->_initModules()
#6 /home/siteName/public_html/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#7 /home/siteName/public_html/index.php(87): Mage::run('', 'store')
#8 {main}";s:3:"url";s:18:"/app/etc/local.xml";s:11:"script_name";s:10:"/index.php";s:4:"skin";s:7:"default";}
网站运作，这件事每天都会发生几次。可能是什么问题？