Is there a virus called the dolly virus?

Because they are unwanted programs that infect your computer, reminiscent of the way an actual virus infects the human body.

Because it makes the computer "sick" and not working right. And computer viruses spread, so it's like another word for saying a computer is "sick" and not working right. Viruses can spread computer...

Viruses are called viruses because, like real-world viruses (e.g., influenza and so on), they 'infect' a computer and often spread throughout it by making copies of themselves and making their code...

Because it is derived from the Ancient Greek rhin meaning "nose".

Yup. In the general sense of the term "virus" (any malware that can be installed on a computer), there are some kinds of malware, usually called downloaders, which can actually download more malware...