Over many years of virus and adware removal I have seen the most common sources of infection are porn sites or pop ups on your computer that say your infected with a virus call this phone number, if you call they will probably infect your computer. If you have young people in the house or want to visit high risk websites; doing your browsing from an Ipad or Linux PC will dramaticly reduce your risk of infection. Linux is another operating system that runs on PC hardware it is similar to windows and has programs that can do all or most of what most of what people need to do. Ubuntu Linux is free download and I am familiar with it's installation. Call me to install it for you. If you have multiple PC's at your house installing linux on one of them for web browsing is recommended.