Exchange 5.5 Service Stopping

I have an NT 4 SP6 Server with Exchange 5.5 running on it and I have a service that keeps stopping. The service is the World Wide Web Publishing Service. When it goes down I can no longer use my Outlook Web Access. It will go down 3-4 times a day. Sometimes I can just restart the service and it will work fine and other times I have to reboot the server before it will start back. I don’t see anything in the event log that relates to this. I have reinstalled SP6 on NT 4 and that didn’t fix it either. If anyone would have any ideas I would appreciate them. Thanks in advance.