Torrent and Spyware

[freedom_for_all]

Spyware name~CWS.LoadAdv.400
Type~Hijacker
Freedom Anti-Spyware used in detection
Number of cws.loadadv found 100+

Imagine my surprise when i did my last spyware scan.
Thee it was all over CWS.LoadAdv.400 path G downlaods. This is my torrent folder. Infected file Lost, Prison Break, Rome, supernatural. These file came from 3 member only torrent sites.
What I want to know is how did they get there. Was the uploader the source.