I'm just posting this so if someone else has the same error if they google they may find this. I was trying to restore a Windows 7 system image off a network drive. It would all go OK till I tried to find the image on the network drive at which point it would either get stuck while trying to find the system image, or give the above error "'An internal error occured while enumerating backup sets". After finding no solution to this, I happened to accept the error, then hit "refresh" on the screen that should have been showing a listing of possible images. And voila, there was my image. So it seems the OS had found the image but for some reason gave the error and failed to show the image in the table. I was then able to restore normally.
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