HTTPStageProcessing Exception in WCF REST service

I am using REST WCF Service, the issue is i am getting HTTP Stage Processing Exception, when i go deep into inner exception level, it said "The underlying connection was closed: The connection was closed unexpectedly."
 
When i debug it to some deep level, i come to know that after serving my request, again the same request has been made, i don't know the reason. But the outsome is pretty obvious for the second request, the undelying connection was closed and hence i get the exception.
 
After lots of hooks and crooks i come to find that there are two properties(say a & b) of type int in the return type of the WCF method, that are responsible for recalling the service method, i comment them and now they are working fine, but this is not the solution.
 
Microsoft's error message does not help me as it is not explained in detail. So kindly guide me towards the reason, how could i resolve it and find it easily from now onwards.
 
Those two properties looks like this
 
        [DataMember]
         public EMP_STATUS EmployeeStatus { get; set; }
 
        [DataMember]
         public EMP_STATE EmployeeState { get; set; }
 
I am working with EF 4.1, if that helps you in anyways. Thanks