Remove the mapping when we're unregistering the service.
diff --git a/providers/bundles/org.eclipse.ecf.provider.msn/src/org/eclipse/ecf/internal/provider/msn/Activator.java b/providers/bundles/org.eclipse.ecf.provider.msn/src/org/eclipse/ecf/internal/provider/msn/Activator.java
index fbad695..3593dae 100644
--- a/providers/bundles/org.eclipse.ecf.provider.msn/src/org/eclipse/ecf/internal/provider/msn/Activator.java
+++ b/providers/bundles/org.eclipse.ecf.provider.msn/src/org/eclipse/ecf/internal/provider/msn/Activator.java
@@ -41,7 +41,7 @@
 
 	void unregisterService(IPresenceService service) {
 		ServiceRegistration registration = (ServiceRegistration) services
-				.get(service);
+				.remove(service);
 		if (registration != null) {
 			registration.unregister();
 		}