Upon installing my apache on windows vista environment I encountered this error “…operation has failed.”. Make sure you have the correct path and dll file on you httpd.conf which is in my case located on this path C:\WEB

LoadModule php5_module “C:/WEB/PHP/php5apache2_2.dll”

and if still the problem persists open the apache monitor click on connect, type in or browse your computer name and restart apache.

You can also find here the quick guide on installing apache 2.2, php 5.2 and mysql 5.