title: Arg_TargetInvocationException random error
body: <p>As title says: there is an <code>Arg_TargetInvocationException</code> that throws exception from time to time when user navigates to Page. Difficulty is that error is unstable and appears randomly. 
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  <strong>What can lead to such kind of error?</strong>
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  <strong>How can it be fixed?</strong></p>
  
  <p><em>Note: I'm using SL4,EF,MVVM.</em></p>
  
  <hr>
  
  <p>Some logs:</p>
  
  <blockquote>
    <p><em>Info Common.Utilities.Logging.NLogWrapper Client:</em> System.ServiceModel.DomainServices.Client.DomainOperationException: Invoke operation 'LogMessage' failed. Exception of type 'System.ServiceModel.DomainServices.Client.DomainOperationException' was thrown.
       <br>at System.ServiceModel.DomainServices.Client.OperationBase.Complete(Exception error)
       <br>at System.ServiceModel.DomainServices.Client.InvokeOperation.Complete(Exception error)
       <br>at System.ServiceModel.DomainServices.Client.DomainContext.CompleteInvoke(IAsyncResult asyncResult)
       <br>at System.ServiceModel.DomainServices.Client.DomainContext.&lt;>c_<em>DisplayClass38.b</em>_34(Object ) </p>
  </blockquote>
  
  <p>Another one:</p>
  
  <blockquote>
    <p><em>Info Common.Utilities.Logging.NLogWrapper Client:</em>
    <br> Load operation failed for query 'GetScenariosAndScripts'. Exception of type 'System.ServiceModel.DomainServices.Client.DomainOperationException' was thrown.
       <br>at System.ServiceModel.DomainServices.Client.WebDomainClient`1.EndQueryCore(IAsyncResult asyncResult)
       <br>at System.ServiceModel.DomainServices.Client.DomainClient.EndQuery(IAsyncResult asyncResult)
       <br>at System.ServiceModel.DomainServices.Client.DomainContext.CompleteLoad(IAsyncResult asyncResult) </p>
  </blockquote>
  
  <p>And in browser I've got error message:
  <br>
  <strong>Unable to navigate to /Start/SomePage: [Arg_TargetInvocationException]</strong></p>