Error 69669 (x11025) Unable to write file during scheduled backup

Hi,
Lately, my weekly scheduled backups have been failing with an error code of x11025 and the message "Unable to write file". This appears to happen after my 3 primary partitions have been backed up - sometime during the backup of my 5 logical drives.
The error occurs only during a scheduled backup; I am always able to successfully backup my drive when I initiate it manually.
Any help would be appreciated,
Thanks,
s660117

 

By the way, I am running Paragon Hard Disk Manager 14 under Windows 7 and am writing to a Seagate external drive.