Actually, Antivirus System Pro along with many other viruses that pose as antivirus software may be very difficult to remove. It will continually send popups in order to distract you as well as prevent you from doing almost anything on your computer. To Manually Remove Antivirus System PRO, you will need another computer with Internet access and Flash drive. First, you have to Find another computer with Internet access and download malwarebytes.org free antivirus software, Ccleaner (http://www.piriform.com/ccleaner/download) and Superantispyware (http://www.superantispyware.com/). You need to Burn these installers to a CD or copy them to a flash drive. After that, you can Boot the infected computer in Safe Mode with Networking.
You must do this with holding down the F8 key during startup. Then, you have to install the three antivirus programs from your flash drive or CD. If Antivirus System Pro prevents installation, you should right click on each installer and choose "Run as Administrator." Next, you need to run Malwarebytes.org first. You can run a Full Scan. Once it is finished, you have to pick "Remove Selected" to destroy all the infected files associated with Antivirus System Pro. Forth, you can run the other two antivirus programs, Ccleaner and Superantispyware as a backup measure. You need to reboot your computer when finished.