The Federal Trade Commission has accused a California pop-up advertising company of digital-age extortion. MSNBC reports that D Squared Solutions allegedly hijacked Internet users’ computers by bombarding them with Windows Messenger pop-up ads — as frequently as every 10 minutes. The ads hawked $30 software that promised only to stop future pop-ups from the company.Windows Messenger is a different beast to Microsoft’s Messenger: it’s supposed to be used for system administrators to send out bulletins to users. Instead D Squared used it to blast annoying messages. The FTC is accusing them of extortion, and with websites like Blockmessenger.com, Endads.com, SaveYourPrivacy.com. and Fightmessenger.com under their control I suspect they have a case.