I wanted to download this wonderful Photoshop-like program called "Gimp". Unfortunately I thought the the name was "Gimpshop". Typing that name into Google took me to a site that looked perfectly normal. Then clicking on the download it installed the right program Gimp, the problem was it installed much more. Tool bars, ad servers, popups, and worse. This version of Gimp was re-written to install more viruses including a root kit that could allow the writer to log everything I typed.
It is extremely rare for us but this virus was so bad that we had to wipe and reload the entire computer. Fortunately I had a full image backup as well as online file backups.
So be careful and do what I say - not what I have done