My backup has failed 3 times this week. Now the only thing that has changed this week is i moved the scheduled time up 2 hours to 730pm instead of 530pm. The drive on which exchange is installed is running very low on space less than 2gb. I am in the process of getting a new server ready for a migration. I have since moved the schedule back to 530pm because i feel it may be conflicting with other scheduled tasks.