If you are using Skype, change the configuration. It seems that Skype also uses the port 80.
I recently updated my Window's wamp version to the latest (64bits & PHP 5.4). It works fine. But then i tried to install the PHP 5.3.1 extension. When i try to use it, Wamp stops on orange and never starts. PHP 5.4 works just fine. This is the first time I try a dual version setup with Wamp. Any thoughts?