Popup Nightmare...
It is possible that your MSN Toolbar is letting those pop-ups in because they are on the "authorized sites" list. If you can check the sites allowed to do pop-ups list in the MSN Toolbar but cannot change them, you may want to consider...
If you have Windows XP, check to see if you have Internet Explorer 7 (IE7). [On the menu bar, click on “Help” and then click on “About Internet Explorer” to view the version.]
If you do have IE7, uninstall the MSN Toolbar and any other Toolbars that have snuck onto your PC. [Use “Control Panel” and “Add/Remove programs” to uninstall the toolbars.] Once you have cleaned the spurious Toolbars out (many of which are actually “Spyware” and/or “Advertisement Ware”), go into IE7’s settings and enable “Popup Blocker”.
Also check the “Settings” for “Popup Blocker” for any web sites you do not want popping up windows. Not all pop-up’s are bad, including the ones used by this forum, so some discretion is advised. That does not solve your current problem but should stop a lot of future ones.
To get rid of the current pop-ups, also download and install “Ad-Aware by Lavasoft” from this link to Download.com:
Ad-Aware 2007 - Reviews and free Ad-Aware 2007 downloads at Download.com
Update the definitions and then run a scan. If the software causing the pop-ups is Advertisement Ware (Adware) or “Spyware”, between “Ad-Aware” and “Spybot: Search and Destroy”, you should be able to kill it.
If the problem software is “Malicious Ware” (Malware), anti-virus programs will not find it (because it is not self proliferating, hence ‘not a virus’ by their definition) and a lot of the Spyware/Adware programs may not be able to remove it, assuming they even see it. Hunting down and killing Malware is not something I like trying to walk people through because you often end up having to edit the registry and replace system critical files after booting with a separate Operating System disk.
Anyhow, a less costly/time consuming option may be to just abandon IE for now and go with the free Mozilla web browser called “Firefox”. Even if you are running Windows 95a or OS9, there is a version of Firefox out there for you and it includes pop-up stopping. You can even download and install ‘Ads-Ons” such as “Flashblock” (used by me to stop all the singing and dancing on websites that lack the ability to show restraint in limiting the number of Flash objects on a page). Here is a link to Firefox by Mozilla:
Mozilla | Firefox web browser & Thunderbird email client