Hi, and Welcome to AntiOnline!

I am assuming that you are using the Microsoft Windows Operating System and a broadband internet connection (DSL or Cable).

First, what you need to do is to turn off File and Printer Sharing for Microsoft Networks. To do this:

Go to the Start Menu, and Open Control Panel. You will see "Network and Internet Connections". Click this.

Next, you will see a screen that says "Pick a Task" and "or pick a Control Panel icon". Under the Control Panel Icons, you will see "Network Connections". Click on it.

Now, you will see some Icons. Open the one for "Local Area Connection" and select "Properties". On the next screen, unckeck the box next to "File and Printer Sharing for Microsoft Networks". Then click OK, and close the windows.

What is happening is that your computer is sending what are called NetBIOS broadcast packets. Disabling the file sharing will limit the amount of broadcasts that your computer sends.

(In all actuality, the ad you saw probably doesn't know that you are broadcasting your IP. It's there to make people who don't know if the computer is doing it or not click on the link to try to sell you something, or wose.)

I would recommend that you install a firewall other than the Windows Firewall that came with Windows XP as well. Make sure you have anti-virus software, and also get a malware/spyware scanner. I would also recommend an Intrusion Prevention System, like Prevx Home (free from www.prevx.com)