If you've encountered Windows 7 Error: New bad clusters were found on the source volume. These clusters were not backed up. (0x8078007D), when running Windows 7 system image backup, there is a simple way to fix the problem.

It took me a while to figure this out and I am not sure what is the main source of this issue. Anyways, if there isn't a real physical problem with bad clusters (and it appears that for this error it's ussualy a faulty report), you should be able to resolve the problem and do your system image backup successfully, by following these steps.

• First, make sure you delete the Windows 7 image Backup folder, typically called: WindowsImageBackup.
• Right click on Computer icon, go to Manage, then click on Disk Management.
• Right click on your C: drive and select option to Shrink Volume.
• Whatever value is automatically suggested, just accept it and click the ‘Shrink’ button and wait for the process to finish.
• Once done, you'll see some Unallocated space.
• Now right click on the C drive and select Extend Volume.
• Click the Next button and press the Finish button.

Run Windows 7 Image backup again. It should work now. I hope this helps, it worked for me.