Doing this appears to make everything work... but only if I type "httpd -k start" ... Just starting the ISP config server doesn't make the httpd work...
Is that normal?
Thts what I have told you several posts above. You mixed up the ISPConfig httpd and the httpd that serves your websites. You have 2 httpd daemons in your setup and all the problems accurred because you added listen directives to the controlpanel httpd server for port 80 manually.