We are experiencing a slight outage on the XML-RPC delivery of advertisements. This only limits impressions on a handful of sites, however, may reduce the number of impressions you'll produce over from September 7 till resolved.
Our webmaster is looking at upgrading our advertising server, this may resolve the issue. However, be assured your run of the network (RON) insertions will continue to display and that all impressions counts will be accurate.
Call your advertising representative if this outage causes any measurable loss of revenue or if you have questions. If the issue isn't resolve by September 25th, then sites will be updated with JavaScript banner rotation.