SAN FRANCISCO -- Chuck Harris remembers when the Internet was fun and he'd spend hours reading his favorite news sites, checking the church calendar, browsing the shops. Then, a few weeks ago, he lost control of his computer. It turned into a giant electronic billboard.
The Web browser was taken over by a company he didn't recognize. Pop-up windows tried to download stuff he didn't ask for. Strange icons kept appearing offering low home mortgage loans and sexual enhancement pills he didn't want.
Harris spent days trying to fix the computer, but the programs had multiplied to the point where he couldn't run anything else and he decided to give up on the machine. Last week, the 68-year-old retired aerospace engineer from Yorktown, Va., shelled out $1,000 for a new computer, but now he and his wife, Dorothy, use it only when absolutely necessary.
"We have just about quit using the computer," he said. "It isn't worth the aggravation."
As if computer users didn't have enough to worry about with hackers, viruses, spam, and other online menaces, now comes a new scourge.
Millions of consumers like Harris have been struggling with a recent surge in what computer experts call spyware or adware.
The terms apply to a broad range of programs that users download from the Internet, usually without intending to. Unlike the occasional pop-up ad, these electronic hitchhikers are hidden programs that stay on the computer's hard drive. They keep serving up advertisements, redirecting browsers to certain Web pages or reporting the computer user's movements and personal information. Or all of the above.
Some spyware comes attached to free, brand-name software that users want and install themselves -- instant-message, video-player and file-sharing programs, for example. A reference to the spyware may be included in the legal jargon of one of those on-screen installation agreements that computer users routinely accept with the casual click of a "yes" button.
Others come unbidden as a side effect of browsing shady sites. Many appear on people's machines simply because they are connected to the Internet.
Experts estimate that tens of thousands of spyware and adware programs circulate on the Internet. For now, the problem of such unauthorized software almost exclusively affects Microsoft Windows users. It's by far the most popular operating system and the same features that make it so versatile also make it easier for intruders to secretly run programs on it.