I turned off "php" using the services control panel that was included with the "custom" iso available a little while back. I didn't turn off web services, but the web server is failing to load because it's trying to call php functions and the php isn't responding. It's generating an error message. I don't know the specifics of what that control panel function does. From what gardnc described I would guess that the php engine is off or disabled perhaps?
To address CharlieBrady's question I don't think it has changed the apache config, in fact I think that is the problem since apache is trying to perform something requiring php and it's not there, so there is an error.
I tried the sequence that RayMitchell described without success.