Internet Explorer now has an effective pop-up blocker, as do Firefox and Opera. The problem of web pages generating multiple pop-up windows which are almost impossible to close is now a thing of the past. Any problems with pop-ups today (assuming you are using an up-to-date browser) are probably a symptom of spyware. These pop-ups typically occur even when the computer is not connected to the internet. The spyware infection itself may have come from an innocent-looking site, perhaps a music or games download site, but the pop-ups themselves are often for pornographic sites.

Removing the spyware that is causing the pop-ups is preferably to blocking pop-ups which are a symptom of malware infection. See the Anti-Spyware page for details of how to remove spyware.

Blocking pop-ups

Update Windows XP to SP2 to take advantage of the pop-up blocker in Internet Explorer, or use Firefox or Opera.

Internet Explorer in Windows XP Service Pack 2 has an effective pop-up blocker included.

There are also third-party pop-up blockers available. Although invaluable in the time of pre-XP SP2 Internet Explorer, the pop-up blocking feature of these products is now largely redundant, except for anybody determined to block even the most persistent of pop-ups, including some of the floating ads that still appear in web pages.

For an excellent list of pop-up blockers, both free and paid, and the opportunity to test your chosen pop-up blocker:

popuptest.com

For information about pop-up ads, comparative test results, and test pages where you can find out if your chosen pop-up blocker blocks the pop-ups you don't want but allows the pop-ups you do:

popup-killer-review.com

For information about pop-up, and a caution about using pop-up blockers:

The Problem with Pop-Up Stoppers aumha.org