Following three simple steps now you can get rid of the pesky and sometimes buggy Windows Genuine Advantage (WGA) notifications:
1. Reboot Windows in safe mode (hold the f8 key while booting and you will get the option to boot in safe mode) and then:
2. Open Registry Editor (regedit.exe) and search for wgalogon folder and delete it. You should backup up the registry beforehand, in case somethiong goes wrong.
3. In your windows directory search for files wga* and delete them.

You are done!
Now reboot back normally and continue your work. Windows Genuine Advantage will not bother you anymore.
Note: I had previously posted a tip which requires a third-party executable. Now it is not required anymore. You can do it yourself by carefully following the guide above.
Warning: Use at your own risk. Backup everything before you do.


Bonus Hint: A better option is to switch to Linux and enjoy all the peace of mind that comes from using Genuine Linux operating system and non-Microsoft software and in not using Genuine Windows software. Additionally laugh all the way to your bank with all the money saved in licensing.