This is a problem to many of them who use windows. This message usually starts popping up after you have attempted to update your windows. The only problems we face are that the screen turns black and you can only change your wallpaper temporarily for a short time. You will also be a little restricted in updating and such things. You will be asked to register and pay to get back the full version. This can be overcome by using simple softwares which can change
the settings and reactivate windows. There are many programs to deal with the problem. One of the program to do it is windows activator.
It can activate windows for as long as you need. The speciality of this program which makes it different is that it does not damage any activating files like the Remove WAT program. This program works on windows 7 and Vista. Here is the link to download:- Download. When running the program Run it as administrator. And note that your antivirus may block the file saying that it is a virus but it is no so deactivate the antivirus before you use it. After you open it
you will see a blue box in which you have to click activate. The activation will start and you have to wait for one or two minuts for it to complete.... You are all done....