virtual domain limit?

Hi, Our web server is running Red Hat 5.2 (Linux). We were recently told that we have exceeded the limit number of domains on our system. We haven't been able to contact our tech support person since then to get a clarification. We recently added four domains, and our web pages promptly went down. He said that we had 167 domains and the limit was set to 165. Actually we only have 78 domains. This is really confusing. I do know that we are running all our domains off one IP using the NameVirtualHost directive in httpd.conf Does anyone know anything about a limit of domains setting? Any help would be appreciated. Thanks, Mike