P2P Computer Security Risk

Risk of using P2P(peer to peer) application e.g. Bit Torrent, Kazaa, Lime Wire.

P-to-P Application Causes Police Security Disaster in Japan
A policeman in Japan was fired after a P2P application, Winny, on his PC caused highly confidential information to reach the Internet.
http://security.itworld.com/4337/070724police/page_1.html