i don't know if this is what you're looking for but i got this off winxpnews.

New Form of Spam Hits Windows XP Computers

Just when you thought it couldn't get any worse, those scumbag spammers have now hit a new low. As if pop-up ads and email spam wasn't enough, now they're taking advantage of the built-in Windows Messenger service. The Messenger service isn't the same as the Windows Messenger. It allows you to broadcast messages to all the computers on your network. For example, if you open a command prompt and type:

net send * Hello World

All the computers on your network within "broadcast" range, will see a dialog box pop up that says "Hello World". Now the dreaded spammers are actually sending these message service messages over the Internet! To say that this is the lowest of the low doesn't do justice to the heinous nature of this kind of spamming. If you see what appears to be a regular Windows dialog box with "Messenger Service" in the title bar and then some spam in the body of the dialog box, you've been "Messenger Service Spammed". If you're running an Internet firewall, you shouldn't be seeing these messages since the firewall should be shutting down the ports the service uses. Another way to stop the messages is to shut down the service. Here's how:

Click Start and then click the Control Panel.
In the Control Panel, click the link on the left side that allows you to switch to Classic View.
Open the Administrative Tools applet.
In the Administrative Tools window, open the Services console.
In the Services console, scroll to the Messenger service entry. Right click on it and click Properties.
In the Messenger Properties dialog box, click the Stop button. After the service stops, click the down arrow in the Startup type drop down list box and select Disabled. Click Apply and then click OK.

Now you're protected from these spammers' form of unusual punishment.