Doing a new build today and I need to install windows 8.1, I managed to find my windows product key but when I go to enter it at the install it says its invalid, even though it is definitely my key, I used "Belarc Advisor" to find it. Could it be because it is already in use? For my new build I have a 500 GB ssd which is going to be the only drive in the new build, currently I have a 1TB HDD. So my question is why won't it let me use my product key and is there any other way to keep this version of windows without having to buy another?
Thanks.