I set Tomcat to use port 80. Why doesn't Apache serve up docuements any more?
When using Tomcat behind Apache, you shouldn't set it to use port 80. Apache wants to use that port.
What's probably happening is that Apache is failing to start properly, since Tomcat is already listening on port 80.
In fact, you don't need Tomcat to listen to any HTTP sockets at all! You can remove the line from server.xml that mentions port 80 or port 8080. Just make sure it's speaking AJP on port 8007 and you'll be able to use Apache as the front end.