NEW YORK (AP) _ Out of nowhere they appear on your computer screen. Sometimes they're unstoppable.
``Pop-under'' ads and other aggressive types of messages are the new wave in Internet advertising, and they have some people so annoyed that they are vowing never to buy from companies that use them.
``The first time, an ad may be cute to look at, but after the 10th time, it sure isn't,'' said Mike Pollock, a 36-year-old New Yorker who spends as many as eight hours a day online.
The last year has been a bumpy one for the dot-com industry. ``As a result, people are willing to push the creative envelope a bit,'' said Patrick Keane, senior analyst at Jupiter Media Matrix, an online consulting firm.
X10 Wireless Technology Inc. did just that with a relentless ad campaign over the past few months for its tiny $80 wireless video camera.
When a user goes to one of the many sites where X10 advertises, its ad immediately opens underneath the browser. When the browser is closed, the ad appears and the user is forced to close it separately.
Virtually overnight, the ``pop-under'' campaign made X10 a recognized name.
According to the online research firm Nielsen/NetRatings, the company had 388,000 unique visitors to its Web site in January, before the pop-under campaign. Nielsen said the number in May was 3.5 million. Unique visitors are counted only once, not every time they visit a site.
Internet chat rooms buzz with angry Web users who want to know how to disengage the X10 ad. Numerous articles have been written on ways to make the ads go away. Even the company's Web site tells people how to turn off the ad for 30 days.
X10 did not return e-mail and phone requests from The Associated Press for comment.
``It is a tightrope they are walking on,'' said Peggy O'Neill, an analyst at Nielsen/NetRatings. ``They have made a name for themselves in a short hurry, and that's impressive. But there is also a backlash out there of people who despise these ads and think less of the brand.''
Pollock is fed up with X10 ads and tries to close them without giving them even a glance. ``I think I am fairly certain that I would never buy anything from X10,'' he said.
Web surfers can use software tools to stop these ads from popping up on their screens. Consumer advocates, however, say that the burden should not be put on computer users.
Pop-under ads are not the only new formats being spotted online. Last month, Ford Motor Co. launched a one-day-only ad May 4 that basically took over Yahoo!'s home page. Animated birds perched on Ford's banner ad began to fly around the screen before eating away at birdseed to reveal an ad for the automaker's new Explorer.
Growing in popularity are ``shoshkeles,'' or ads that look like cartoons floating over text and pictures. They have been used by such companies as Monster.com and Domino's pizza. One ad for JetBlue Airways featured a picture of one of its planes ``flying'' over the Web site Travelguys.net.
Also being seen more often are ``superstitial'' ads, which load into a computer's temporary memory while a user is viewing a Web page and appear instantly when the person clicks to another page on the same site.