Before using quick heal anti virus I used to watch movies and songs downloaded from any site which used to contain viruses and because of that viruses enter in my computer and started creating problem and started hanging , sometimes it get switched off automatically while using.then I call my computer service operator he told me that the problem is due to virus and recommended me about quick heal anti virus.and I immediately told me to put in my computer.after putting that in my computer it doesnot let any virus to enter in my computer and if any site has virus it inform me from previously that dont download from this site virus is there and I download from some safe side.if any virus enters also accidently it removes.its very useful and my computer is working very fast after using it.