Well tell yopur friends to chande all there passwords that have been hijacked try a strong password like
1rW@5yz0-P3nL a password like that would take forever to crack and also tell your friends to get a trojan scanner and scan there full system for trojans http://www.agnitum.com/download download tauscan from there
http://www.anti-spy.com/anti-spy-netsafe.htm also download this anti spy ware package i think it is good for a trial this will scan your computer for key-loggers and spy ware hope this helps
peace