Popup windows don't have some usual windows parameters, i.e. buttons, menus etc. And so Popup Annihilator Pro kill all these windows. But if you want you may add certain Url to White list and popups from it will be accepted. Moreover you may configure Popup Annihilator Pro for killing all windows from certain Urls.
Popup Annihilator Pro is one of the fastest products in compare with other popup killers. It is written on Microsoft VC++ while the most of others popup killers are written on Borland C++ Builder or Borland Delphi. The most of popup killers occupy a lot of windows resources because they check system for popups each period of time. Popup Annihilator Pro uses another technology and so it occupies minimal system resources.