Getting error The given assembly name or codebase, 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel\v4.0_4.0.0.0__b77a5c561934e089\System.ServiceModel.dll', was invalid.

Hi, I am getting this error suddenly.

The given assembly name or codebase, 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel\v4.0_4.0.0.0__b77a5c561934e089\System.ServiceModel.dll', was invalid.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.IO.FileLoadException: The given assembly name or codebase, 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel\v4.0_4.0.0.0__b77a5c561934e089\System.ServiceModel.dll', was invalid.

Source Error:

[FileLoadException: The given assembly name or codebase, 'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.ServiceModel\v4.0_4.0.0.0__b77a5c561934e089\System.ServiceModel.dll', was invalid.]
   System.ServiceModel.Activation.ServiceHttpModule.BeginProcessRequest(Object sender, EventArgs e, AsyncCallback cb, Object extraData) +0
   System.Web.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +556
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +288

Any help / pointers will be appreciated.