Here it is:

<system.serviceModel>
<bindings>
<customBinding>
<binding name="customBinding0">
<binaryMessageEncoding />
<httpTransport />
</binding>
</customBinding>
</bindings>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true" />
<services>

  <service behaviorConfiguration="WcfService.ServiceBehavior" name="MyAPP\_WF\_WCF.WF.Infrastructure.ListValueWF">
    <endpoint address="" binding="customBinding" bindingConfiguration="customBinding0"
     contract="MyAPP\_WF\_WCF.Interfaces.Infrastructure.IListValue" />
    <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
    <host>
      <baseAddresses>
        <add baseAddress="http://localhost:8731/Design\_Time\_Addresses/MyAPP\_WF\_WCF/WF/Infrastructure/ListValueWF/" />
      </baseAddresses>
    </host>
  </service>

 .....


</services>
<behaviors>
  <serviceBehaviors>
    <behavior name="WcfService.ServiceBehavior">
      <serviceMetadata httpGetEnabled="true" />
      <serviceDebug includeExceptionDetailInFaults="false" />
    </behavior>
    <behavior name="MyAPP\_WF\_WCF.Workflow1Behavior">
      <serviceMetadata httpGetEnabled="true" />
      <serviceDebug includeExceptionDetailInFaults="true" />
      <serviceCredentials>
        <windowsAuthentication includeWindowsGroups="true" allowAnonymousLogons="false" />
      </serviceCredentials>
    </behavior>
  </serviceBehaviors>
  
</behaviors>

</system.serviceModel>

Thanks Mark... But how can I do that? I have actually tried to comment all the code inside the WF functions so they would just do nothing. And still they were giving the Async Exception occasionally ...

I have developed a Workflow and published it as WCF webservice on IIS. The ServiceReference.ClientConfig contains the following binding for each webservice:

        <customBinding>
   <binding name="CustomBinding\_IListValue">
                <binaryMessageEncoding />
                <httpTransport maxReceivedMessageSize="2147483647" maxBufferSize="2147483647" />
            </binding>

....
</customBinding>

    </bindings>

    <client>
        <endpoint address="http://IPAddress/MyService/GetListValue.svc"
            binding="customBinding" bindingConfiguration="CustomBinding\_IListValue"
            contract="SRListValue.IListValue" name="CustomBinding\_IListValue" />

....
</client>

I then created a Silverlight 3 webapplication that references the published svc webservice. The crossdomain.xml and clientaccesspolicy.xml are in the wwwroot of the webserver. When calling the silverlight webapplication, the call sometimes works perfectly and sometimes give the Async_Exception. We monitored it through Fidler and it sometimes gives the 500 http error that doesn't say much and sometimes it passes through. We have been struggling with this for a week now. Appreciate any help in the matter. Thanks Grace