Most everybody is aware of the pop-ups that you can get when you visit a web site. Internet Explorer 7.0 and Firefox 2.0 do a pretty good job of blocking most of those. To test your browser you can go to PopupTest. I did and found IE let 3 slip through, and Firefox failed to catch 2.
These aren’t the ones that bother me though. It’s the ones that originate in your own computer that have me bothered. They are caused by adware that you have allowed to become installed on your PC. Often they come with innocent looking freebies like those found at Zango. Zango like several other similar companies is interested in stuffing ads down your throat.
If you want tech details there is a great report out at AffiliateFairPlay.com. Beware that there are a lot of tricksters out there claiming to remove or block adware. These bad apples will install bad stuff instead of remove it. Stick with the proven names if you want to battle adware. The only two I can recommend are Ad-Aware and Spybot.
You can’t make your PC dummy proof by adding something like Norton Internet Security. You still have to be careful of the downloads you grab. Take your time and do a little search to see it they are known to carry spyware or adware. It can save you a lot of grief in the long run.