When you try to back up data by using Windows Azure Online Backup, is the backup process is unsuccessful? If so this hotfix may be for you.
The Windows Azure Access Control Service (ACS) certificate uses a new certification authority (CA) chain and this can prevent communication between it and the Windows Azure Online Backup Agent. This communication fails because the backup agent cannot verify the server certificate that is presented by the Azure ACS service.
For all the details and a download link for the fix please see the following: