Print out these instructions as we will need to close every window that is open later in the fix.
Reboot your computer into Safe Mode with Networking. To do this, turn your computer off and then back on and immediately when you see anything on the screen, start tapping the F8 key on your keyboard. Eventually you will be brought to a menu similar to the one below:

Using the arrow keys on your keyboard, select Safe Mode with Networking and press Enter on your keyboard.
Windows will now boot into safe mode with networking and prompt you to login as a user. Please login as the same user you were previously logged in with in the normal Windows mode. Then proceed with the rest of the steps.
Download Malwarebytes' Anti-Malware, or MBAM, from the following location and save it to your desktop:
http://download.bleepingcomputer.com/malwarebytes/mbam-setup.exe - Malwarebytes' Anti-Malware Download Link (Download page will open in a new window)
Once downloaded, close all programs and Windows on your computer, including this one.
Double-click on the icon on your desktop named mbam-setup.exe. This will start the installation of MBAM onto your computer.
When the installation begins, keep following the prompts in order to continue with the installation process. Do not make any changes to default settings and when the program has finished installing, make sure you leave both the Update Malwarebytes' Anti-Malware and Launch Malwarebytes' Anti-Malware checked. Then click on the Finish button.
MBAM will now automatically start and you will see a message stating that you should update the program before performing a scan. As MBAM will automatically update itself after the install, you can press the OK button to close that box and you will now be at the main program as shown below.

On the Scanner tab, make sure the the Perform full scan option is selected and then click on the Scan button to start scanning your computer for Fake Windows Activation screen related files.
MBAM will now start scanning your computer for malware. This process can take quite a while, so we suggest you go and do something else and periodically check on the status of the scan. When MBAM is scanning it will look like the image below.

When the scan is finished a message box will appear as shown in the image below.

You should click on the OK button to close the message box and continue with the Fake Windows Activation screen removal process.
You will now be back at the main Scanner screen. At this point you should click on the Show Results button.
A screen displaying all the malware that the program found will be shown as seen in the image below. Please note that the infections found may be different than what is shown in the image.

You should now click on the Remove Selected button to remove all the listed malware. MBAM will now delete all of the files and registry keys and add them to the programs quarantine. When removing the files, MBAM may require a reboot in order to remove some of them. If it displays a message stating that it needs to reboot, please allow it to do so. Once your computer has rebooted, and you are logged in, please continue with the rest of the steps.
When MBAM has finished removing the malware, it will open the scan log and display it in Notepad. Review the log as desired, and then close the Notepad window.
You can now exit the MBAM program.
As many rogues and other malware are installed through vulnerabilities found in out-dated and insecure programs, it is strongly suggested that you use Secunia PSI to scan for vulnerable programs on your computer.
The source:
http://www.bleepingcomputer.com/virus-removal/remove-fake-windows-activation Answered Jun, 14 2011