Cybia's right : these are not pop-ups. Pop-ups are HTML pages which appear while you are surfing. Their code is embedded in the page you are visiting. Pop-ups killers mentionned above won't do against them. The messages you get with a "OK" button are network messages (if you click on OK nothing happens). This is a facility that is given to network masters (in a firm for instance) to send a message to all connected users at once. They appear when you are connected, wether you are surfing or not. Actually, it is some firm that scans open connections and send you these messages without you doing anything. If you want to get rid of them, you have 2 options : 1- If you're not in a network (or don't need this facility for your home network), then do as Cybia says. 2- If you're at work, ask the sysop. He/she will know what to do.