Dealing With Pop-Ups

There are at least three varieties of pop-ups, and the solutions vary accordingly.

After you finish with this episode of malware / unwanted network traffic, improve your chances for the future.

Messenger Service Pop-Ups

This will be a text only message, and will only hit you when you're online. A Messenger Service pop-up can't contain a clickable link. The window will be titled "Messenger Service".

This type of spam has become quite common over the past year or so, and unintentionally serves as a valid security alert. It demonstrates that you haven't been taking sufficient precautions while connected to the Internet. Your data probably hasn't been compromised by these specific advertisements, but if you're open to this exploit, you most definitely open to other threats, such as the Blaster Worm that still haunts the Internet. Install and use a decent, properly configured firewall.

Messenger Service of Windows
Messenger Service Window That Contains an Internet Advertisement Appears
Stopping Advertisements with Messenger Service Titles

If you're using AOL, you'll either need to find a 3rd party firewall that is compatible with AOL, or switch to a real ISP that is compatible with the real Internet. This is because AOL is an on-line content provider that ignores international networking standards in favor of its own proprietary products, and has deliberately made its connection software incompatible with both WinXP's built-in firewall and WinXP's Internet Connection Sharing feature. AOL's proprietary connection applet is deliberately designed to preclude your setting/adjusting any of its properties, to include enabling/disabling WinXP's ICF and ICS.

Whichever firewall you decide upon, be sure to ensure UDP ports 135, 137, and 138 and TCP ports 135, 139, and 445 are all blocked from Internet access. You may also disable Inbound NetBIOS (NetBIOS over TCP/IP). You'll have to follow the instructions from firewall's manufacturer for the specific steps.

Please make sure that you only block the above ports from Internet traffic. If you have a LAN, and are using Windows Networking, you do not want to block those ports between your computers. Only block those ports between your computers and the Internet. Read the firewall / router manual.

You can test your firewall at:

Gibson Research (ShieldsUp!)
Sygate Security Scan
Symantec Security Check

Be especially wary of people who advise you to do nothing more than disable the messenger service. Disabling the messenger service, by itself, is a "head in the sand" approach to computer security, similar to Security by Obscurity. The real problem is not the messenger service pop-ups; they're actually providing a useful, if annoying, service by acting as a security alert.

Regular Browser Based Pop-Ups

This will be an HTML message, and will only hit you when you're online. A browser based popup will probably contain clickable links. The window title will vary.

There are many ways of dealing with annoying, but not illegal, advertising pop-ups. Here are two.
Get the free Google Toolbar. Hosts file blocking works on this problem also.
Blocking Ads, Parasites, and Hijackers with a Hosts File.

Adware / Spyware Pop-Ups

This will be an HTML message, and can hit you when you're online, or offline. An adware based popup will probably contain clickable links. The window title will vary.

Please see Dealing With Malware (Adware / Spyware) to continue.