I have been running a Version 11 application server for a number of years. Suddenly today I am getting a "400 Bad Request" error message. We are using port 443 and having to include the port in the URL. We also use Always Up as we are running multiple application servers on one server. We have tried stopping and starting the application server, rebooting the main server and republishing. Any suggestions on what to try next?

Thanks for any help anyone might be able to give.