Try the following steps until the issue is resolved:

A.  Verify that the target drive has sufficient space for the backup files

B.  Delete this old scheduled backup in the Windows Tasks folder:

1. From the Task bar, click Start, Run.
2. Type Control SchedTasks and click Enter (or browse to C:\WINDOWS\Tasks)
3. Select Advanced from the Menu Bar.
4. Select View Hidden Tasks.
5. Remove the scheduled backup invoked by schedule 7 for database (old database name).

C. Change the folder to which the backups are being placed.