Unknown Virus Infected my computer

[KAMANA]

Last week I installed a program on my computer. When I installed this program my anti-vrus didn't detected it as a suspicious or an illegal program. Later I came to know it was a trojan infected program. Now I'm not able to update my anti-virus. Even I'm not able to do System Restore. The files which are infected seem to contain w32.pinfi virus. I even get a Blue screen sometimes and the computer hangs.

[Steve123]

You would have to avoid System Restore. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.System Restore doesn't deletes the Virus. Hence if you restore the settings it would probably restore the Virus. Reboot your system into Safe Mode by tapping the F8 key .Now perform a full scan.

[Milton.J]

Since your Anti virus is not able to update itself there are chances that your firewall is not allowing it to do so.You would have to check the filter levels that are set for the firewall.For that you can use: Click Start -> Run -> type in cmd and on the command prompt screen that appears type in ipconfig /flushdns.Also Delete the cookies and temporary files.This can be done as: Open the internet explorer -> Click Tools -> Select Internet Options -> Click on the General tab -> Click the Delete Files button -> When the box opens, put a check in Delete All Offline Content -> Click OK.

[Spyrus]

There might be a chance that the anti virus was not properly installed.Try installing another anti virus.You can install 2 anti virus at a time. After installing the second anti virus reboot your system into safemode and perform a full scan. Another way is try Kasperskys online checker to get rid of the unknown virus.
Click here to run the Kaperskys online file scanner.