Antivirus system pro alert

I keep getting a pop up from Antivirus system pro alert stating that my computer is being attacked by an internet virus.

Says it's a Bankerfox.A threat & it's asking me if I want to block it. How do I get rid of it?

Please download the current version of HijackThis from HERE

• Double click and run the installer.
  
• It will install to C:\Program Files\Trend Micro\HijackThis\hijackthis.exe
  
• After installing, you should get the user agreement, press accept and Hijack This will run.
  
• Select Do a system scan and save a log file. This will open a notepad file of everything Hijack This found, copy and paste it back here.