received key, entered key, system rebooted. windows now lost activation. Unable to activate. for some reason, my system restore doesn't have any restore points, even though system restore is still ON. This came up after trying to activate:

Unable to activate Windows 8 Pro with Media Center. (Error code: 0xC004C4AA)

You might see this error after you used the Add Features to Windows 8 app to upgrade your current edition of Windows. The Windows 8 Pro with Media Center edition can only be activated on PCs that had Windows preinstalled, or Windows was purchased on the Windows website or at a retail store. To fix the problem, you need to install Windows with the product key provided to you in an email or with the DVD. If you think you have received this message in error, contact a Microsoft Customer Support representative