Apache problem with hostname on OSX 10.8.4
This problem seemed to slowly evaporate when I started using sudo apachectl -k stop (though this could be just coincidence).  It now seems I can switch between servers using 

sudo apachectl stop and /opt/local/apache2/bin/apachectl start, 

and then back with 

/opt/local/apache2/bin/apachectl stop and sudo apachectl start

no problem.  I haven't been able to find any documentation on apachectl -k (beyond apachectl help).