UPDATE: This issue was resolved on 10/28/2013.
On Saturday, 10/26, there was an issue with a redundant server for Connected backup, which affected the ability of some desktops and laptops to complete backups. We believe the problem was fixed by Monday 10/28, 6pm.
If you continue to experience backup problems, please contact your local desktop support staff. To escalate, please open a ticket via ServiceNow.