<A HREF="http://www.techworld.com/security/news/index.cfm?RSS&NewsID=11020">New"ransomware" that locks up a person's PC</A> is demanding $35 in order to return control to the user, a security researcher has warned this week. The extortionists tell victims of the Delf.ctk Trojan horse to dial a 900 number, said Alex Eckelberry, CEO of US security developer Sunbelt Software Distribution. That number can be traced to "passwordtwoenter.com," a payment processor also used by hardcore pornography Web sites to charge for access to their content, added Eckelberry. Users infected with the Trojan horse see a full-screen message posing as an error generated by Windows, according to screenshots posted by Eckelberry on the Sunbelt company blog earlier this week.