WCF Issue related to KB976769v2

Today we have seen a strange issue in consuming WCF service for our user control. The following error have been came up after turning off the Custom Errors in Web.Config file of SharePoint Web application.

Configuration Error
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately. 

Parser Error Message: An error occurred creating the configuration section handler for system.serviceModel/bindings: Could not load type 'System.Security.Authentication.ExtendedProtection.Configuration.ExtendedProtectionPolicyElement' from assembly 'System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

Source Error: 
Line 131:  </behaviors>
Line 132:
Line 133:  <bindings>
Line 134:   <wsHttpBinding>
Line 135:    <binding name="MyWSHttpBinding" maxReceivedMessageSize="2147483647">

My Environment Details:

• SharePoint 2007
• Windows Server 2003

Solution

After removing KB976769v2 from "Add-Remove programs" from control panel in all my web-servers fixed the problem.