Hello The other day I wanted to reinstall my Windows 8 OEM(believe it is "core") I started the recovery process, but every time it told me, that it could not continue because a "required drive partition is missing". Basically this meant for me that I was unable to make a full system recovery. I then remembered that I had already bought a Windows 8 pro key so I just downloaded the Windows 8 Upgrade Tool from Microsoft's website, entered the key and made a fresh reinstall. Now I no longer have Windows 8 Core, but Windows 8 Pro. However, since I had already used the key on my old computer then my Windows 8 Pro is not activated on this computer because the key has already been used. And here is my question, what do I do. I really want it to go back to the Core version I had before, but I can't use my original Product key for the OEM version on the upgrade Assistants. I can't "use it on a retailversion." Before I made the recovery in the first place I did make a USB media of it. Meaning I installed the recovery media on a USB, but as mentioned, it did not Work because the "required drive partition was missing". I then tried to use this USB recovery media (which I made from the OEM version) and make a recovery from it while having Windows 8 pro installed, but instead of installing the old Windows 8 Core it reinstalled Windows 8 pro with the key I ordered from Microsoft and used on my old computer. So what do I do? I really want it to go back to what it used to be. With Windows 8 "core" OEM - as when I ordered the laptop.