Disclaimer The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.
You'll get this error when using WCF/IIS and host headers.....fortunately a fellow colleague Paul Glavich figured it out!!! Well done Paul! (It involves an IIS reshuffle, you may be able to do something within a custom WCF Binding.)
Remember: There is a limit on the number of IIS Websites you can have on a single machine.
