As some of you may have noticed (we heard from you on Twitter!) we had an issue with the Windows Live ID service between 9 and 10AM PST this morning. Due to the failure of one server, Windows Live ID logins were failing for some customers, and this increased the load on our remaining servers. We took the problematic server offline and brought a new server into rotation. We identified the root cause and fixed it in less than an hour, but it took a while to resolve the logjam that had built up in the meantime, and to redistribute the load to normal levels.
As with all incidents like this, we will fully investigate the cause and will take steps to prevent this from happening again. We’re very sorry for the inconvenience this may have caused to you, our customers and partners.