415 Unsupported Media Type when WSE is NOT configured

I have a web service that runs fine on my Windows XP. However, when I deploy to the production server, the web service returns 415 Unsupported Media Type when calling.

I have seen this error when WSE is not enabled on the client. The problem is, the web service is NOT using WSE. so I did the usual, uninstall ASP.Net, reinstalling, adding asmx extension to IIS, same error.

Now I need to fire a debugger to see what’s going on. Surprisingly, Microsoft.Web.Services3.dll is loaded even when there is no trace of it in my projects. Now I probably know what’s going on. There is another web service in a different virtual directory that uses WSE.

OK, I will isolate my web service to a new application pool. Well, that does not help. In the end I have to add WSE configuration to both my web service and my Windows client.