i live my magento website but its show error :  headers; headers already sent in /home/tantransh/public_html/test/app/Mage.php, line 766

Trace:
#0 /home/tantransh/public_html/test/lib/Zend/Controller/Response/Abstract.php(115): Zend_Controller_Response_Abstract->canSendHeaders(true)
#1 /home/tantransh/public_html/test/app/code/core/Mage/Core/Model/App.php(1246): Zend_Controller_Response_Abstract->setHeader('Content-Type', 'text/html; char...')
#2 /home/tantransh/public_html/test/app/code/core/Mage/Core/Controller/Varien/Front.php(80): Mage_Core_Model_App->getResponse()
#3 /home/tantransh/public_html/test/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(202): Mage_Core_Controller_Varien_Front->getResponse()
#4 /home/tantransh/public_html/test/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#5 /home/tantransh/public_html/test/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()
#6 /home/tantransh/public_html/test/app/Mage.php(683): Mage_Core_Model_App->run(Array)
#7 /home/tantransh/public_html/test/index.php(87): Mage::run('', 'store')
#8 {main}
