Computer was Dell laptop with Windows 7 Professional SP1 COA. Then I did the free upgrade to W10 Pro. Then I used Aomei Partition Assistant to resize my 128GB SSD so I had 55GB free. I reinstalled W7 and now have a dual boot machine with both 10 and 7. (MBR) The only issue is: after using Windows 10 and then booting to Windows 7, I receive a message that Windows 7 isn't geniune. It's not a huge problem - I simply re-enter the Windows 7 key from my COA and it's activated again. But why does it happen? When I boot Windows 10, does it think (or report) that no other Windows OS can exist on the laptop?