On Unity 4.2.1, I'm doing a Dirt backup from Unity, a member server, to an Exchange server, a domain controller. Both servers are Windows 2003. I have a mapped drive from Unity to the backup folder on Exchange. I created a backup account in AD. I can backup to the mapped drive on the Exchange server when I'm logged in to Unity with the backup account (I can also backup locally). But, when I schedule the backup to run after hours, it always fails with "could not write to destination path" in the Event Viewer. If the scheduled backup runs while I'm logged in, it will work with no problem. But, when I schedule it and log out, it will fail. I'm using the two hop method for SQL. If I schedule to backup locally and I'm logged out, it will work. Any ideas what am I missing here? CSA is not installed. The Windows firewall service is not running. Are there other permissions or something? Thanks.