It is important to remember that this exception is thrown when there is a blank line at the top of the PHP script.

Martin Burger: “I am so sorry for bothering you all. Needless to say, there was an empty line in one of my included scripts (pretty much at the and of a long chain of includes...)”

[ http://www.nabble.com/Zend_Controller_Response_Exception ---Cannot-send-headers--headers-already-sent-td17608333.html ]