Don't try to call "win32_start_service_ctrl_dispatcher" too late in your code. You'd trigger a #2186 error : "The service is not responding to the control function." (from commande line) or a #1053 error : "The service did not respond to the start or control request in a timely fashion." (from services GUI).
Try not to load a bunch of PEAR classes before to register php script as Service like I did.
Another good hint, to get a verbose version of the return code, you can call "NET HELPMSG ###" from command line where ### is your error code.