Hello, recently I was wondering what Windows 8 Pro offered in terms of additional features etc so I activated it with a serial key. However, it now says that my Windows isn't activated and I keep getting a full screen window appear telling me to activate Windows. I purchased my PC new with a legitimate copy of Windows 8. If I reinstalled Windows, would I need a serial key or would it go back to standard Windows? Any help is greatly appreciated as this is a problem I really would like to fix. Thanks.