I am getting that error on this first line:
MapPoint.Pushpin pushpin = order.Pushpin;
if ( pushpin != null )
order.Pushpin = null;
I have an Order object (contained in an OrderList object) and I associate a pushin with each order so that I can keep track of them. And when I'd like to delete them all I go through my list and call the above code for each order. But the first line generates the "RPC Server is unavailable" error.