I picked up a virus from hell and can't do a thing now. Window after window blocks me from even opening the PC. I need to install a new OS, but I'm not sure if I can even do that. I know I'll need a new number to enter so it will be a full install. It now has 8.1 os.. how can I tell which OS to buy that will run okay in it. Pavilion 15-NOIOUS . I can't remember the ram..etc, and there's no way for me to see anything. Also.. will putting in a new OS remove the virus ?