Sly "Spyware' Sneaks Past Viruses As No. 1 Complaint Of PC Users; Critics warn programs do more than push ads; they cripple machines.(A)

Byline: BRIAN DEAGON

Major League Baseball threw a curveball Wednesday at companies that use so-called spyware to place pop-up ads online.

MLB Advanced Media -- the league's online arm, which is jointly owned by 30 teams -- said it would no longer work with companies that rely on spyware or adware. Pop-up ad sellers use such software to track the surfing habits of Web users. The data are then used by advertisers to target consumers with selective ads.

The result, say baseball officials, is that unauthorized ads have appeared on MLB Web sites.

"We are a victim of spyware," said Jim Gallagher, MLB Advanced Media's senior vice president of corporate communications. "Ads are popping up on our site that are not from partners of MLB Advanced Media. We believe spyware is unlawful and unethical, evasive and undermines the credibility of our sites as an advertising medium."

It's the latest volley against spyware, which is increasingly seen as an invasion of privacy. Critics charge the software is potentially malicious and may be used for unwanted snooping.

But there's a difference between spyware and adware, providers of the software say, and they shouldn't be grouped together.