Had a challenge yesterday that took me a while to figure out so I thought I'd share what I've learned...
CWP installs its own Apache (v.2.2.27 as of the date of this post) running from /usr/local/apache/bin/httpd
The standard Httpd from CentOS is still installed on the system though, which could lead to unexplicable errors should the /etc/rc.d/init.d/httpd script file was to revert to its original format.
I had the need for mod_proxy, forcing me to compile the needed modules from the Apache sources and, somehow, in the process, the /etc/rc.d/init.d/httpd script file got changed to call the standard instance of httpd.
All of a sudden, my CWP's vhost conf stopped working!
If that happens to you, just open /etc/rc.d/init.d/httpd to see if it goes to the right path and pid.
Hope that helps someone else as it took me quite a few hours to figure it out!