Windows 7 - Backup images: Conflicting number of backups and size

I have an odd thing going on with the Windows 7 backup utility. I use backup only for system images. Backup tells me that my system images are currently taking up about 70 GB of space, which is roughly the maximum amount of space Windows is allocating to system images. However, there is only one image in that location taking up about 9 GB.

What's even more odd is that Explorer shows that in the 'Computer' view, the amount of free space on the drive holding the image(s) agrees with the 70 GB figure. But, when you browse the folders of the drive, only 9 GB of images is accounted for. So, I downloaded a 3rd party file/folder browser, which agrees that only 9 GB of images exists and reports that the free space on the drive as being 61 GB (70 minus 9) greater than what Windows 7's Explorer reports in the 'Computer' view.

Consequently, because Windows believes there are 70GB worth of images, it deletes my only image before it backs up the next image, leaving me again with only one image.

Has anyone seen this behavior before?