Have you come across this issue HTTP could not register URL http://+ . Another application has already registered this URL with HTTP.SYS
Are you self hosting a WCF library service inside a console or windows forms application? Then the most likely cause of this problem is that you have the library project contained within your same solution.
The problem happens because the WCF Service Host running at the same time as your custom host application. You run or debug your app and when your host initialises the WCF stack, you will see an AddressAlreadyInUseException as in the above pic. This is happening because the WCF Service Host in Visual studio is already listening on the same address...
Basically remove the wcf lib from the solution and reference it. When you run the host you should now be able to open it.
ServiceHost host = new ServiceHost(typeof(ClientHost));
Now there should be no errorJ!
Rick Rainey's suggested a fix to the config file which doesn’t work for me, but may for somebody else which prevents removing it from the project. http://blogs.msdn.com/rickrain/archive/2008/02/14/Preventing-the-WCF-Service-Host-from-launching-in-Visual-Studio-2008.aspx
I have not seen if this bug exists in 2010 yet.. I will update when I check it..