While I haven’t been doing any troubleshooting yet of this issue, we are also experiencing the same thing. Old, existing Windows 7 images work just fine, but the new machines were getting are failing on restore exactly as you stated. When we get a new machine in, we typically image it right out of the box, so we could restore to factory default if need be – but these test restores now fail. FWIW, these are ALSO Dell Machines (OptiPlex 7010) – maybe it’s just a DELL issue? Haven’t tried an HP box yet.