Is the issue is still persisting even after complete format of your machine?
> If so please do mannual update the antivirus application you have.
(You can do it by downloading an update file in another machine and transfering the file into your machine using a pendrive.) I recommend you to use Bitdefender or Avast (free version) in your machine.
> Reboot your machine and logon to safe mode.
> Now scan your machine with the Antivirus application.
(You can also scan your machine with following application
Spywareblaster, Spybot, ADWARE PERSONAL, Malwarebytes, Trojan remover)
> Once you are done with scnning your machine with the above mentioned application, clean all the temporary files and cookies using Ccleaner application.
> Now restart your machine and logon to normal mode.
This help you to clean your machine.
Kindly let us know if the above steps didn't help you or the issue still persists even after following them. Please get back us the results at your convinience.
Thank you :)