How to block Messenger Service ADs?

These pop-ups can be prevented by installing a pop-up blocker. Often times, these new windows display advertising that can interfere with your ability to see the content on the page you're trying to read. Adding the Ad related Domains to the Restricted Zone in Internet Explorer is a good idea. Refer to the following MS-KB articles to learn how to stop pop-ups from a particular webpage.

Messenger Service Advertisements

If the title bar reads as "MESSENGER SERVICE" with gray Ads, then it the famous Messenger SPAM. This is applicable only for Windows 2000 and Windows XP. The "Messenger Service" [different from Windows Messenger IM] is responsible for transmitting these text-based messages. While disabling the Messenger Service can stop the pop-up ads, it's not sufficient in the security point of view. These messages arrive to your system because there is a way for someone to transmit data to your computer via TCP and UDP ports [UDP ports 135, 137, and 138; TCP ports 135, 139, and 445 137]. This means, some intruder can do nasty things on your computer with these ports open.

The HIGHLY RECOMMENDED method to prevent these type of pop-up and to harden the security of your computer is to install a firewall application (such as Zone Alarm), or use the Windows XP Firewall. Windows XP SP2 turns off the Messenger Service by default, and enables the Windows firewall. This blocks the ports required for Messenger Service data transmission.

To enable the Firewall in Windows XP
For Windows XP SP2 systems:

If you're using Windows XP, and haven't updated to SP2, please do it immediately.

Click Start, Run and type Firewall.cpl
Select On (recommended) button, and click OK.
Never connect to internet without enabling the Firewall. Otherwise, there are fairly good chances your system gets infected. Finest example is the RPC NT Authority Shutdown caused by Blaster Worm, which infects "unpatched" and "unprotected" computers.

Note: If using a third-party firewall application, you don't have to enable the built-in Windows XP firewall.