There is a Microsoft Technet discussion on a similar problem. It has to do with the SYSTEM RESERVED partion and a space issue. A couple of workarounds are discussed there. The basic is that free space on the System Reserve partition is too low.
Most likely fix quoted from discussion:
Sorry for the delay. From the information sent by some customers my email, we see that USN journal on the System Reserved partition is getting turned on by some application (most probably third party). This eats up space on the volume and hence causes backup to fail. Please follow the following steps to determine the size of the USN journal on the System Reserved partition.
Assume that your System Reserved partition is F:
1. Lauch cmd -> Run as Administrator
2. Fsutil usn queryjournal F:
This will output the settings of the USN journal.
3. Check the Maximum size field. This gives you the space used (in bytes in hex) by the USN journal on the volume.
4. Open calc and set in hex mode and paste the value.
5. Change mode to decimal and divide by 1048576 (ie. 1024 * 1024) to get the number of MB.
6. If you see this to be anything of the order of 30 MB, backup will fail owing to lack of space.
Can you let me know if this is the case? Also, the typical type of applications that use USN journal are apps that crawl the file system to track changes. Ex: Backup, indexers etc. If you know of any suspicious application, do let us know.
Meanwhile, in order for your backups to work, please exclude system image from your backup and run your backups. Please note that this will back up only your user files.
Edited as the links where not working for me...