I know, my dear, which is why I recommended the thread to you. No body wants a virus or malware on their computer, if it was a shared computer or not, which is why we're trying to help you, and tell you that Norton is proven to be one of the most over rated (in the worst way) antivirus programs ever. Because not only does it point out alot of programs that infact aren't viruses, but it also misses plenty that are. If you don't want to read the thread, I'll write it here.
If you want a reliable antivirus, that its not only free, but makes your computer unimaginably squeaky clean, I personally recommend you get both of these programs: Microsoft Security Essentials, and Adwcleaner. Microsoft Security essentials is made by Microsoft itself, as shown in the title. MSE is good with normal maintenance, and scheduled, regular checkups. It's free to download from the Microsoft website. However, MSE is almost perfect, but not quite. This is where Adwcleaner comes in. MSE is good with catching and stoping the big guys, but alot of the smaller, quieter ones, it overlooks. Adwcleaner, while it might look fishy (I know I thought it was too when I first saw it) but it works wonders. The first time you run it, it will find small little files that you didn't even know were in your computer. It checks files, directories, shortcuts, and even extensions from your internet browser. I've installed both of these programs on all of my computers, and all of my family's computers, and will continue to in the future. Having both combined, is a truly deadly duo.
TL;DR: I recommend Microsoft Security Essentials, and Adwcleaner. Installing both on a computer will make a computer so squeaky clean you might even get suspicious on how you haven't gotten any viruses lately.
If you want links, just send me a PM, and I'll give both of the download links to you ^^
