Index: win_iocp_io_service.ipp
===================================================================
--- win_iocp_io_service.ipp	(revision 81044)
+++ win_iocp_io_service.ipp	(working copy)
@@ -407,8 +407,9 @@
         return 0;
       }
 
-      // If we're not polling we need to keep going until we get a real handler.
-      if (block)
+      // If we're not polling we need to keep going until we get a real handler,
+      // unless we have been stopped.
+      if (block && ::InterlockedExchangeAdd(&stopped_, 0) == 0)
         continue;
 
       ec = boost::system::error_code();