Fiddler not sniffing SOAP traffic from ASP.NET website
What's the client of the web service? ASP.NET?
ASP.NET traffic isn't proxied unless you configure ASP.NET to use a proxy. It's possible/likely that the app.config or machine.config changed such that traffic is no longer getting proxied?
You should have a look at this section: http://www.fiddlerbook.com/fiddler/help/hookup.asp#Q-DOTNET
If you want to view the http traffic between your web site and your web service on your development machine, and don't want to change your machine.config.
One easy solution is to change the Application Pool Identity of your web site to use your own credentials of the current logged on user. This means that your web site will adopt your proxy settings and will now redirect to Fiddler.
Make sure the web service you are calling (from IE) is not http://localhost/yourwebservice
Fiddler will not intercept localhost traffic from IE, use http://machinename/yourwebservice instead.