Are you saying that you are getting pop ups without the browser being open?
On Windows 2000 and Windows XP there is a service, called "Messenger", often unfortunately referred to as the "Windows Messenger", that is used to present what can best be called "network messages" to a machine's user. This is not an instant messaging application, but rather software that runs in the background, listening for incoming messages, and popping up a very simple box containing the message when one arrives. The most common example might be in a corporate environment when you send a document to a network printer. The messenger service handles the pop-up message that the printer sends back when it has finished.
Unfortunately the Messenger Service has been exploited by SPAMmers to pop-up unwanted advertising messages on unprotected machines on the internet. The average user has absolutely no need for the Windows Messenger Service, and thus it can safely be turned off. To do so, go to Start -> Programs -> Accessories -> Administrative Tools -> Computer Management -> Services & Applications -> Services. Double click "Messenger", and set the "Startup Type" to Disabled. You can also "Stop" the service at that same dialog.
If your popups are coming from your browser, you may want to follow the steps listed on this page and post a log for the experts to review.
http://www.geekstogo..._Log-t2852.htmlJohanna