New York's attorney general sued another Internet pop-up advertising company Tuesday, accusing it of secretly installing malicious programs on personal computers and sending ads through "spyware" that is already installed.

Eliot Spitzer said Direct Revenue LLC has installed millions of pop-up ad programs that also monitor the Internet activity of users. He asked a state court to stop the practice.

"These applications are deceptive and unfair to consumers, bad for businesses that rely on efficient networks to do their jobs, and bad for online retailers that need consumers to trust and enjoy their online experience," Spitzer said. "We will continue to side with consumers in their fight for control of their desktops."

Spitzer, who is seeking the Democratic nomination for governor this year, already has sued one company on allegations they install spyware and adware — software that can be downloaded onto personal computers generally without the computer user's full knowledge.

Spitzer ultimately settled with Los Angeles-based Intermix Media Inc., which also developed the popular social-networking site MySpace and is now part of News Corp. (NWS).

In the civil lawsuit, filed in state Supreme Court in New York, Spitzer claims Direct Revenue or its distributors offered free games, browsers or software without mentioning that they would come with VX2, Aurora, OfferOptimizer and other adware downloads.

After such "drive-by downloads," which he said his investigators got when visiting at least 21 Web sites, the company can track consumers' Web activity and deliver pop-up ads, Spitzer said.

Spitzer said the software thwarted consumers' removal attempts and sometimes reinstalled itself.

Officials with New York City-based Direct Revenue didn't immediately respond to a request for comment.

Spyware and adware often land on computers by hitching a ride during visits to porn and gambling sites or as part of downloads of free games and screensavers. Infected computers can be rendered unusable as ads continually pop up.

In October, the former chief executive of Intermix Media, Brad Greenspan, agreed to pay $750,000 in penalties after Spitzer accused the company of secretly installing adware and spyware on millions of home computers.

Spitzer had accused Greenspan of directing employees to bundle adware with other free programs and to make the software difficult to remove.

Intermix also agreed to pay $7.5 million in penalties over three years.

Spitzer's latest lawsuit also names Direct Revenue's former chief executive, Josh Abram.

Spitzer said Abram told a distributor in an e-mail that "we have a very stealthy version of our adware product," adding that "these will not be caught."

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