Normally that will pop up if someone has used a activation bypass or something with activation is corrupt in Windows, such as the files that do with activating have been corrupted or changed, or a key code is blocked.
I have had people complain that their windows would say it is not activated after running my Windows Repair and every single one of them was using a activation bypass hack. The hack they where using added Microsoft to the hosts file to block the activation and of course my repair restores the original hosts file. So wasn't a bug or problem but it was just the repairs doing their job.
So as for this one that you posted, if you where using a activation hack then you will either need to use a good key or reapply the hack (If MS didnt block that method yet, they do block ones they find) or some files on the system are messed up and if so run sfc /scannow
Shane
