>>I see the Request class implements IDisposable so it's presumably accessing unmanaged resources - and the above code doesn't guarantee that Dispose() is called. Might just be possible that it's holding something open that the compiler needs. IAC you should wrap it in a using block.
>
>Viv,
>
>Can you clarify how should I apply using to that code?
>
>Thanks again.

Maybe:

public static string Invoke(string input)
        {
            using (CurrentRequest = new Request())
            {
                //........
             }
        }

But ideally the class containing this method should probably implement IDisposable and call Request.Dispose() there.