So basically I had a very bad virus/infection on my computer that wouldn't let me see my screen and when I logged in I just got a black screen and mouse cursor. I took it in to TigerDirect and they said they have to reinstall my operating system which would basically erase everything (I play games so I didn't care that much) but it did cost me $100. So what is this type of infection called? And how can it MAINLY be avoided again? The only thing I download on a day to day basis is World of Warcraft Addons on CurseClient.com not the actual client. But I did go on some free TV websites that I never used but work.