ispconfig uses the /root/ispconfig/scripts/shell/check_services.php script to verify if all services are up and running and sends an email if a service is down. After installing VMware on the same box I received a warning message for 'webserver down' every 30 minutes.
This is due to the fact the above script uses 'localhost' as the server name to check if apache is running. After installation of VMware, 'localhost' is bound to VMware and is no longer configured to Apache. My really simple solution to get rid of this message is to replace 'localhost' in the script with a valid IP address on which Apache is running.
The more permanent solution would be for check_services to look for a configured IP address in the httpd.conf file and use that as a verification address. Unfortunately, I don't have the time to write the code myself, but I would consider this a useful Request for Enhancment.