There’s been a lot of publicity about pop-up windows, and most of it hasn’t exactly been rave reviews. But it hasn’t always been this way.

In fact, pop-up windows were a positive component in the beginning. Created long before tabbed browsers, their purpose was to present information without interfering with the current browser window.

These days, due to security risks as well as the annoyance factor, a standard feature among browsers is to block or control pop-up behavior. But before you start telling your browser or other privacy programs to block all those pop-ups, you need to understand why they happen and what you should really be doing about them.

Most pop-ups are part of the content from the Web site the user is visiting, containing either requested information or info the site thinks one might like. But other pop-ups are just spam that’s both invasive and malicious in nature.

These types of pop-ups are actually an alarm telling you that something’s wrong with your computer and you need to fix it. Let’s divide pop-ups into two general categories — normal and alarms.

Normal pop-ups

Some pop-ups are information you’ve requested — music or video content from a link you just clicked or a download you requested (hopefully from a trusted site). Web-access e-mail programs use pop-ups to create or reply to e-mail, which mimics a traditional e-mail client.

In addition, some pop-ups are targeted advertising marketed specifically to consumers visiting a Web site. If you find yourself getting too many of these advertisements, it’s probably due to the sites you’re visiting.

In general, all of these types of pop-ups are the kind you want. And if not, you can easily dismiss them with a click on the X. These are the pop-ups you should be controlling with your browser or privacy program. But the other types of pop-ups are the ones you want to see — because they’re alerting you that something’s wrong with your system.

Alarm pop-ups

You don’t want to block the pop-ups that indicate a problem with your system — these are the ones you want to see and take action on to resolve. For example, if pop-ups are launching through the Windows Messenger Service, you’ve got a potentially serious problem.

To get rid of these pop-ups, you need to turn off the Messenger Service. Follow these steps:

  1. Go to Start | Run, type services.msc, and click OK to launch the Services applet.
  2. Scroll down to find Messenger.
  3. Right-click Messenger, and select Properties.
  4. On the General tab, select Disabled from the Startup Type drop-down list, and click OK.

This is a serious security issue. While the Messenger Service pop-up starts with data on UDP 135, this pop-up indicates that the Windows networking ports (i.e., TCP/UDP 135, 137 through 139, and 445) are open to the public. This pop-up is an alarm that you need to block these ports with your firewall.

Another type of alarm pop-up is the browser flood. As soon as your browser opens, you start receiving a swarm of pop-ups. This browser “spam” is telling you that spyware/adware is running on your system. While this is usually why people enable pop-up blockers, that’s comparable to rolling down your window and sticking your head outside so you can see to drive.

What’s the real solution? Clean your Windows! Blocking the alarm doesn’t solve the problem. If your system has experienced this type of behavior, start shopping for a spyware/adware removal tool (maybe several), and clean your system.

Final thoughts

While pop-ups can be a pain, they sometimes indicate a more serious problem. Don’t ignore all pop-ups — investigate the problem and make your system safer.

Worried about security issues? Who isn’t? Automatically sign up for our free Security Solutions newsletter, delivered each Friday, and get hands-on advice for locking down your systems.