Cannot send headers; headers already sent in /home/canadian/public_html/index.php, line 15

#0 /home/canadian/public_html/lib/Zend/Controller/Response/Abstract.php(115): Zend_Controller_Response_Abstract->canSendHeaders(true)
#1 /home/canadian/public_html/app/code/core/Mage/Core/Model/App.php(1226): Zend_Controller_Response_Abstract->setHeader('Content-Type', 'text/html; char...')
#2 /home/canadian/public_html/app/code/core/Mage/Core/Controller/Varien/Front.php(80): Mage_Core_Model_App->getResponse()
#3 /home/canadian/public_html/app/code/core/Mage/Core/Model/Url/Rewrite.php(204): Mage_Core_Controller_Varien_Front->getResponse()
#4 /home/canadian/public_html/app/code/core/Mage/Core/Controller/Varien/Front.php(166): Mage_Core_Model_Url_Rewrite->rewrite()
#5 /home/canadian/public_html/app/code/core/Mage/Core/Model/App.php(349): Mage_Core_Controller_Varien_Front->dispatch()
#6 /home/canadian/public_html/app/Mage.php(640): Mage_Core_Model_App->run(Array)
#7 /home/canadian/public_html/index.php(95): Mage::run('', 'store')
#8 {main}