I noticed exactly the same and would just like to add weight to the argument for imaging using the multi-partition single disk option. I think it may be specific to windows 7, not sure.
Jigar:
I would use the multiple partition option. Leave the OS set to Windows 7. It never fails.
I think kirksec is right regarding the single partition settings. I have only ever been able to get it to work in that situation. In the past it was always problematic for me so I stopped using it.