What Does the Error Mean?
Now that you know a little about the validation process, what do you do if you encounter a Microsoft Security Essentials Windows 7 product key is invalid error message? What does it mean?
If you have received such as message, usually when first installing Security Essentials, it means that the product key that is registered for your copy of Windows 7 does not come up as a valid product key. First, don't panic. Many people who purchased legal copies of Windows 7 ran into this issues when the operating system was first released. The first thing you should do is make sure that you have activated your copy of Windows 7. If you have just received a Windows 7 computer or have just updated your current PC to Windows 7, you have a month to activate your copy. Simply go to the START menu and type in "activate" and then choose "Activate Windows" from the list of options.
If you have activated Windows, but yet MSE still says your copy is not genuine, try to validate your copy by using the Genuine Advantage software. You can also try activating Windows 7 by telephone; when you are within the screen to Activate Windows, just choose the "by phone" option instead of "activating online".
If you have tried the above and MSE is still giving you issues, trying another antivirus program may work for you. There are several free versions that you can download, like Avast, AVG, and Kapersky.
Image content @ Microsoft Security Essentials