Ports in NT

We use Vista Plus as a reporting tool for Oracle Applications. I’m having trouble with the application simply not responding. When users try to login, it’s as if the application service isn’t running (of course it is). When I do a netstat while users can’t login, I can’t see the port that the application uses but as soon as I restart the service, up pops the port. Has anyone seen this type of behavior before? I’ve spent a number of hours with Quest technical support and they believe it’s an NT problem. I’m inclined to agree but don’t know how to troubleshoot this one. I’ve scoured TechNet to no avail. Any help would be greatly appreciated by me and the 100 or so users that use this application.